“Well, I guess I know what I like,” Hefner said when I asked him if he didn’t think it odd that as he got older and older, his girlfriends remained the same age, all in their 20s and all conforming to an unoriginal model of perky blond buxomness. He was in his standard daywear — red silk smoking jacket and black silk pajamas — and sipping a Pepsi while sitting in the mansion’s largely bookless library underneath a huge breast-baring ceramic bust of Barbi Benton, one of the few brunettes ever to catch his eye. “You do give up something in the process,” Hefner went on, acknowledging that most of his girls have never listened to his kind of music — jazz and the big bands of the ’30s and ’40s — and have never heard of Betty Grable and Alice Faye (who probably imprinted that sexy blond template on him in the first place). “But you gain something, too. There is something wonderful in the student-teacher relationship — the rediscovery, the chance to have a relationship with a younger woman. It permits you to see the things you love with a fresh eye, makes them exciting again. And I don’t think there’s any question that surrounding yourself with youth keeps you younger.”

This avuncular, nurturing Hefner, and not the sleek, night-owl playboy of decades past, is the one who emerges on “The Girls Next Door,” and may account in part for the success of that show. “The Girls Next Door,” which the E! network began showing on Sunday evenings in 2005, surprised even people at E! by attracting a huge viewership primarily composed not, as you might imagine, of heavy-breathing teenage boys but of women in the very profitable 18-to-34 age group. Even Kevin Burns, a friend of Hefner’s who produced the show, has trouble explaining its appeal. One of his more recondite theories is that the three girls (besides Wilkinson, there were Holly Madison and Bridget Marquardt) happened to illustrate the Aristotelian triad of ethos, logos and pathos, or honesty, brains and emotion. Hef, on the other hand, as the critic Daphne Merkin has pointed out, seems less lascivious than distantly, absent-mindedly affectionate. He’s like the TV dad on “Father Knows Best” and other Stone Age programs.

People in the Playboy company talk a lot about the “brand,” a sort of emanation from the magazine that they believe has in some ways transcended Hef himself. Hefner’s daughter, Christie, who was chairwoman and C.E.O. of Playboy Enterprises from 1988 to 2009, told me that once when she was in China, where there are hundreds of stores selling Playboy merchandise but where the magazine itself cannot be published, someone asked when her father had joined the company. The brand is a label that can be attached to stuff — not just thongs and rabbit-head necklaces like the one Carrie Bradshaw wore for a while in “Sex and the City,” but bar glasses, pool cues, bath and shower products and tank tops for dogs — and there is a huge and growing market for this merchandise overseas, especially in Asia and Eastern Europe.

The brand, not the magazine, is the moneymaker these days. Playboy is getting back into the gambling business, licensing its brand to casinos in Macau and Las Vegas. The Playboy television channel, meanwhile, is trying to advance from raunchiness to coolness with its new Saturday-evening program, “Brooklyn Kinda Love,” in which Brooklynites all appear to be childless, pierced and tattooed. An elderly pipe-smoking gent in a bathrobe would be weirdly out of place here. Yet the Playboy brand still depends at some level on the imagery of the debonair smoothie who created the magazine, the kind of guy who knows his way around the bedroom but is also well informed about neckwear, stereos and shoe care and who gives big parties at his mansion.

Hefner is “iconic,” his friends and associates like to say, and lately there has been an effort to burnish and preserve the icon. In 2008 Steven Watts published “Mr. Playboy: Hugh Hefner and the American Dream,” an authorized biography that treated its subject with the care and depth usually reserved for statesmen and political figures. Last summer, Brigitte Berman came out with “Hugh Hefner: Playboy, Activist and Rebel,” an adulatory documentary film (made with Hefner’s cooperation) that emphasizes his many contributions to civil rights and freedom of speech. For years now the producer Brian Grazer and the director Brett Ratner have been talking about making a biopic, possibly starring Robert Downey Jr., and there have even been discussions about a possible Hefner musical.

What happens if, or when, the icon is no longer personally available is inevitably on the minds of many people associated with Playboy. Though he is not pushing a succession plan, Hefner is pleased that his sons — Marston, who is 20, and Cooper, who is 19 — have begun to take an interest in the magazine. He told me that Cooper, an avid cartoonist, reminds him a lot of himself at the same age. To judge from a couple of brief conversations, however, neither of the Hefner boys shares the braininess of their 58-year-old half-sister, Christie, a summa cum laude Brandeis graduate; nor, for that matter, do they display much of the self-inventiveness, born both of awkwardness and ambition, that characterized their father at the same stage in his life. They’re sweet and slightly spacey and seem a little young for their age — a result, probably, of growing up in a world that is a real-life version of what is for most adolescent boys only a guilty fantasy.

“I prefer to think of it as when he’s not active, not when he’s not around,” Christie Hefner said, talking about the future. She and Richard Rosenzweig, the executive vice president of Playboy Enterprises and a longtime friend of Hefner’s, like to imagine that he will become a beloved, eternally brandable figure like Walt Disney. “It will be easier to perpetuate my story when I’m not around,” Hefner told me. “Because then nobody will be pissed off that I’m still getting laid.” He also pointed out that his mother lived to be 101. Then he went back upstairs to his legendary bedroom, which these days is a bit of a mess: stacks of old movies on tape and DVD, knickknacks and tchotchkes everywhere, childhood photographs on the mantel, panties dangling from a chandelier and, nestled together on a sofa, a couple of hundred stuffed animals. It looks less like a love nest than the cave of a hoarder unable to let go.