Playboy founder Hugh Hefner is photographed at the Playboy Mansion in the Holmby Hills area of Los Angeles in this April 2006 file photo. Hefner is offering to buy the remaining shares of the media empire he founded in the 1950s.

Chicago ? Hugh Hefner wants to buy out the portion of the Playboy empire he doesn’t already own in a bet that the iconic brand can still bring in profits even if the ink-on-paper magazine is past its prime.

Hefner, who founded Playboy magazine more than a half-century ago, is apparently not alone in thinking Playboy can keep swinging into the digital age. A few hours after Playboy Enterprises Inc. announced Hefner’s offer Monday, the corporate parent of rival Penthouse magazine said it will also make a bid.

But it does not appear that the silk pajama-clad 84-year-old — who owns about 70 percent of the company’s voting shares and 28 percent of the nonvoting stock — will budge.

Playboy said Hefner made it clear in his buyout proposal that he is not interested in a sale or merger. The company said Hefner expressed concern that selling Playboy could threaten the brand and its legacy. Hefner has instead proposed joining up with a little-known private equity firm, Rizvi Traverse Management LLC, to take Playboy private.

The offer comes as print advertising is in a tailspin and the company has stretched its brand thin trying to wring profits through leasing its famous bunny ears for everything from cigars to slot machines.

Hefner, who serves as Playboy’s editor-in-chief and chief creative officer, is offering $5.50 per share in cash, a nearly 40 percent premium above Friday’s closing stock price of $3.94. Shares of the company gained 41 percent Monday. Based on the number of shares outstanding on April 30, Hefner’s proposal is worth $122.5 million and values the company at about $185 million.

If the deal goes through, Hefner will have a major turnaround effort on his hands.

The racy magazine that Hefner launched in 1953 had its most popular years back in the 1970s. It has struggled to lure readers and advertisers as the Internet supplants print as the top purveyor of adult content. Falling revenue has forced several rounds of layoffs at the company since 2008.

Playboy magazine, which along with its websites generated 44 percent of the company’s

$240 million in revenue last year, sold 311 ad pages for its U.S. editions last year, down from 765 in 2000, according to the Publishers Information Bureau. Its average circulation has fallen by about a million copies over the same period to 2.02 million. That’s down from more than 5.6 million in 1975.

These days, most of the company’s income is drawn from licensing the Playboy brand for consumer products such as men’s underwear, women’s lingerie, watches and energy drinks.

Its licensing unit reported income of $21 million last year, followed by $9.9 million from the company’s television properties and just $1.6 million from the magazine and its Web site. Factoring in corporate overhead, costs related to layoffs and write-downs on the value of its assets, Playboy reported a net loss of $51.3 million in 2009.

The company’s stock price has tumbled since hitting a peak in 1999 of more than $32. It traded between $2.30 and $5.22 over the past year before jumping $1.61 to close at $5.55 on the potential buyout Monday.