When the results of the Egyptian census were published recently, Khalil Ibrahim could not read them, but they only confirmed in pages of grim statistics what he and millions like him already knew - the poor of Cairo live in some of the world's most densely populated and overcrowded neighborhoods.

He lives with his wife and two children in a single room.There used to be eight people living there, he said, but four other children have married and moved away. There is no kitchen, and all families in the building, perhaps 50 people, share a single toilet.

In the streets around the tiny shop where Ibrahim makes his living by ironing other people's clothes, those circumstances are the rule, not the exception.

He lives in the district known as Rod al Farag, according to the census the most densely populated community in this teeming city. Rod al Farag, named for a Moslem holy man, has 261.348' residents per square mile. Washington, D.C. has 12,065 per square mile, New York 26,318.

While Ibrahim put down his iron to talk about himself, the chaotic street life of Cairo swirled about him - children, pushcart vendors, goats, donkeys, buses, bouncing off one another in incredible profusion in the filthy streets and alleys.

Ibrahim, a toothless illiterate of 70, spoke without bitterness, perhaps because he has always been poor and knows no other life. He pays the equivalent of about $2.50 a month for his room, he said, and the living conditions are not his greatest concern.

"When I was a boy," he said, "good food was cheap and plentiful. But children today cannot grow up as strong as I did."

His neighbor, Salah Hafez, who sells Mobil Oil Co. kerosene from a tank mounted on a cart, lives a bit better. He divorced his wife, he said, and so he has only one son living with him in his $1-a-month room. With an income of $7.50 a month, he is not doing badly, by Rodal Farag standards but he is worried that his business will fall off as more people turn to butane gas for their cooking.

Rod al Farag, home to more than a quarter-million people like these, is Cairo's most crowded district, but not its poorest or more squalid. Built in this century, it at least has passable streets and substantial buildings.

The next most crowded, Bab el Sharela, inside the walls of the old city, is a medieval warren of shanties and should-width alleys that is perhaps more typical.

But the differences are marginal. Collectively, these poor, crowded neighborhoods of Cairo and their look-alikes in Alexandria represent a crushing economic burden on the country and a political time bomb as well.

President Anwar Sadat has set the construction of new housing as the country's principal domestic goal and has ordered a strategy of "invading the desert" with new cities to spread the population out. But the census results offer little encouragement.

They show that Egypt's total population of 38.2 million is now 44 per cent urban, up from 37 per cent in 1960.

Unlike the self-sustaining peasants and farmers, the city-dwellers consume billions of dollars in government-subsidized food every year, and have long since surpassed the government's capacity to provide them with adequate transportation, health care, water supplies or schooling.

Egypt's population, jammed into the three per cent of the land that is habitable, is growing by 2.3 per cent a year. That is slower than in the 1960s, according to the census, but experts say the decrease is not nearly enough to allow Egypt to make any inroads into its problems.

Of the total population, more than 31 per cent are children under 12 Adult illiteracy is given as 56.5 per cent, a substantial decrease from the 70 per cent of 1960, but it is still 71 per cent among women, most of whom cannot read the birth control information that is made available to them.

The census figures show that a quarter of all Egyptians who have reached marriageable age, 16 for females and 18 for males, have never married. This figure, which has grown rapidly over the past decade, is attributed by Egyptian analysts to the economic difficulties that make it hard for young people to support children, and to the obstacles young couples face in finding a place to live.