Spend a day running around with Dave Barry on a book tour, and two numbers jump out at you. Both are in the 60s.

One: Dave — no one addresses him as anything else all day — is 66. Two: “60-something,” which is the answer to, “So, how many book tours have you been on?”

The first is surprising because it seems impossible that the mop-topped, eternally baby-faced, eternally smart-aleck columnist/author/comedian, who once wrote a book titled “I’ll Mature When I’m Dead,” is older than the president of the United States. By nearly 15 years.

The second is surprising because — well, because he’s still alive.

“I was running down 54th Street in New York yesterday, holding a tuna fish sandwich, to get to a radio interview on time,” he’s saying this week between D.C. readings, “and I turned around and yell at the publicist, while we’re running, ‘I’m too old for this.’ ”

It’s one of his few straight lines all day. But he shows no signs of flagging.

Here’s what his D.C. day looked like, promoting his 39th book, “You Can Date Boys When You’re Forty,” a collection of essays about being the father of a teenage girl (and other stuff):

Board a train in New York early, arrive at Union Station at 10:30 a.m. Television interview. Speech/reading/signing at the National Press Club at 1 p.m. Across town to XM Radio interview with Bob Edwards. Back across town, check in at hotel (by now it’s after 4 p.m.), and then he’s got another hour-long radio interview by phone, after which he has to hustle up to Politics and Prose, where he has an evening speech/reading/signing.

By noon the next day, he’ll be in Atlanta, back onstage.

His overall tour schedule: 18 personal appearances in 14 metropolitan areas in 15 days, from Miami (where he lives) to New York to Seattle. That isn’t include dozens of television, radio and newspaper/blog/Web interviews in between. The days stretch on for more than twelve hours. And there’s always a plane tomorrow morning.

“It’s like if you’re a band — say, the Beach Boys — and you come to town to perform. Well, you’ve got to do your song, you’ve got to do your hits,” he says, late in the day. “I’m not tired yet. Next week? Next week, I’ll be tired.”

He’s been doing this sort of touring for both the hardcover and paperback versions of his books — collections of columns, essays, novels — for three decades, ever since his weekly 800-word humor column at the Miami Herald blew up into a pop-culture staple. He won the Pulitzer Prize, he had a television sitcom (“Dave’s World”), and “Peter and the Starcatchers,” a young-adult novel he wrote with Ridley Pearson, is a bestseller that became a Broadway musical that won five Tony Awards.

Is he still popular?

The signings at his appearances can last as long as an hour.

“My dad’s a big fan and I’ve been reading him since I was twelve,” says Lucy Novick, who stood in line for 45 minutes at Politics and Prose to get her book signed — and to get her picture taken, with a couple of friends, beside the man himself.

“He had this great story about an exploding Pop-Tart,” says Devon Mackenzie, also in line, explaining how she became a fan.

Of course, while touring is hard, he’s got the onstage patter down solid.

At each stop, he gets up behind the podium, amiable, fast-paced, playing off the audience, performing more than reading, a stand-up comic. His material on this tour revolves around his life at home in Coral Gables, a Miami suburb, with his wife, Michelle Kaufman, a sportswriter at the Miami Herald, and Sophie, their 14-year-old daughter. The hits: the family tour to Israel (a camel is involved), a Justin Bieber concert (which a camel might have improved upon) and Dave’s sophisticated analysis of “50 Shades of Grey.” Also, his funeral plans (mimes, snipers, no camels).

Somebody calls out a question, asking if his daughter minds being written about.

“If she does, I guess she can pay her own way through college,” he says, drawing a huge laugh from the packed crowd. “Daddy needs material.”

His idol is Robert Benchley, the early 20th-century comic essayist who, with famed wit Dorothy Parker, was a founding member of the Algonquin Round Table. Both thrive upon this sort of epigrammatic wit about the ways in which daily life — marriage, politics, child-rearing, driving, dogs, sports — is unintentionally funny or just plain bizarre. It’s PG-rated observational humor, never mean-spirited or profane.

Vintage Benchley: “In America, there are two classes of travel: first class, and with children.”

Vintage Barry: “If a woman has to choose between catching a fly ball and saving an infant’s life, she will choose to save the infant’s life without even considering if there are men on base.”

By now, it’s a little after 9 p.m. The bookstore crowd has wound down, all the books are signed and the staff is putting away the folding chairs. It’s been a 14-hour day. Dave is finished. Dave can go back to the hotel. Dave has to get up early tomorrow.

Dave has another two weeks on tour.