"I don't think a prize can change a man's life," says Isaac Bashevis Singer, who won the Nobel Prize for literature last week.

He leans in the air-conditioned limousine which takes him from Channel's studios, where he was interviwed on Panorama to the Mayflower for newspaper interviews to National Public Radio, where he will have yet another.

"My life is more or less the same," says Singer, the immovable object, totally unperturbed by the carefully controlled turmoil into which he has been planged since winning the most prestigious and lucrative of all literary awards eight days ago.

"Before the prize, of course, I did not give every week 50 interviews but it's more or less the same - I think about the books and plays I will write, the people I will put in them. I think my friends are more excited about the prize than I am."

At 74, nearly bald with a small fringe of white hair, a ready smile, a neat business suit, Singer looks like everyone's idea of the kindly old family doctor - back in the days when doctors made house calls and remembered the names of all their patients.

A small man: thin and wiry, he moves with an easy grace that belies his years. He has the courtly manners of the Old World, where most of his novels and short stories are still set although he has been a New Yorker for 43 years. At elevator doors, he stands back for his escort - a woman his publisher, Farrar Straus & Giroux who must be one-third his age.

"For the past week" - Singer is stepping spryly into the limousine and settling his small frame comfortably in the corner - "I didn't do any writing at all. I was so busy, people calling interviews. I decided it's not a misfortune if I don't write for a week."

Of the many messages of congratulation he received during the week, the most memorable, he thinks was a phone call on Wednesday from President Carter.

"I was at home, resting and they called and told me the president wanted to talk to me. And then, in a minute or two, he came on and we talked. I said, "Today is Yom Kippur and I get a call from the president - a day to remember."

"I don't remember exactly what he said - something kind and clever. Did he sound like he has read my books? I don't know - maybe he did: maybe he will read them in the future. I want all the readers I can get."

The car moves smoothly down Wisconsin Avenue and, as he talks, Singer's eyes dart from side to side, picking up small details of the passing scenery.

Automobiles are not his chosen mode of travel. "When I am at home, on the Upper West Side of New York," he says, "I walk 60 to 80 blocks everyday - it is my exercise and all the entertainment I need.

"I seldom go to plays or movies and never watch television unless there is a presidential election or something. I love music - classical music - but my knowledge of it is almost zero. When I hear it. I am delighted and I say, 'I must listen to it more often,' but there is no time."

"Prize," a frequent word recently in Singer's vocabulary, comes out sounding a bit like "price," and he pronounces a few other words with a barely detectable accent. Otherwise, only a few slight irregularities of syntax hint that the eight novels, seven short story collections and 11 children's books he has had published in English were all originally written in Yiddish.

"There are so many writers who write in English," he explains. "I think it's good that there are a few who write in Yiddish."

But there is more to it than that.

Thinking about his first language (he calls English his second), Singer meditates on his past, his personality, his ideals:

"I still think and feel in Yiddish. It is the language of my childhood, the language of my roots - and I don't think it is good for a writer to get too far away from his roots.

"I dream in Yiddish. I know because my wife, Alma, tells me. Sometimes I wake up talking to her in Yiddish without even noticing it. I think our dreams come largely from our childhood. In dreams, as in stories, the dead are alive. At my age, my dreams are full of people who have died. So are my stories."

On a normal day, which he has not experienced since he won the Nobel Prize, Singer usually spends about two-and-a-half hours writing. "I used to sleep very late," he says, "but at this age I get up about breakfast in a restaurant and by about 11 I'm usually ready to write until lunchtime - about 1 or 2.

In the afternoons, I do some editing or translating or meet people. Being a writer is a full-time job, even though I don't spend much time writing."

Although he has more than two dozen books in print, Singer belives he is "not very prolific. I have many books but I am an old man. A lot of my books were written a long time ago."

For a minute, he turns from answering to questioning: "Do you know what has happened in the chess match?" Told that Korchnoi has won another game and tied the matchs, he is surprised: "Such a comeback for an old man.

"I used to play a little chess - not very well. Once a master asked me if I could play and I said, 'A little.' So we played, and for a few moves he would say: 'How unusual,' or 'How extraordinary.' But after 10 moves, he said, 'you know that you are a patzer (an amateurish player), and I said, 'Yes. I know that I am a patzer.'

"It is such a beautiful game - you can't hide anything. It's like literature; you can't hide anything in that either."

All of his characters, Singer says, are people I have known - I make a few changes put them in a different time and place but I have tried to invent people and have found that for me, it's a mistake. I think the Almighty has invented so many characters that I don't need to.

Sometimes people recognize themselves in one of my characters, and once in a while they are right. But I used to know a man in New York who always saw himself in the villains and always wanted to sure the author. It was a strange kind of modesty."

Ideas come to him from old memories and from things that happen to him every day. "Sometimes I take an event from modern New York and put it in Poland 50 years ago, or vice versa."

A veteran journalist who has done hundreds of interviews himself (in Yiddish for New York's Jewish Daily Forward), Singer is equally at ease on the other side of the process. He can talk easily in a television studio, standing in the Mayflower lobby while his escort checks him in or at rest in a quiet corner. But he can be perplexed by small physical problems.

Up in his room seated in a comfortable chair, he tried to turn on the lamp and looks concerned when a tug on the switch produces no light. When someone tightens the loose bulb his face lights up: (That's) what was wrong."

"Every morning" Singer says, "I wake up with appetite to write. It doesn't always work but I enjoy it even when it is going badly. I hear writers say that writing is a great pain for them and I can't understand this. What kind of writing can they do if it's a pain?"

He is a firm believer that a writer can learn from everything that happens to him, "even a prize."

It has meant more for other writers - Solzhenitsyn, for example - he concedes. "Perhaps it helped Solzhemitsyn to get out but I don't need anyone to let me out. I am where I want to be."

His current major project (besides assembling a short-story collection to be published next year) is his authobiography - for which he now has material to write a surprising new chapter.

"I am happy about this prize as much for the surprise for anything else," he reflects a speculative gleam in his eye - and you can tell that he is lining up his life mentally like the plot of a story.

"If people know what would happen next in their lives, life wouldn't be worth a penny. Sometimes people ask me whether I would like to live my life over again and my answer is that I would - but only if I couldn't know what was going to happen next."