There is something Donald Trump says he doesn’t know.

In an interview with the Associated Press to talk up All-Star Celebrity Apprentice, the billionaire businessman admitted the entertainment industry throws him for a loop.

“If I buy a great piece of real estate and do the right building, I’m really gonna have a success,” he says. “It may be more successful or less successful, but you can sort of predict how it’s gonna do. But show business is like trial and error! It’s amazing!”

The ubiquitous brand mogul and media maestro loves to recall the iffy prospects for The Apprentice when it debuted in January 2004. In its first season, it averaged almost 21 million viewers each week. And it gave Trump a signature TV platform that clinched his image as corporate royalty.

The two-hour premiere of All-Star Celebrity Apprentice (Sunday at 9 p.m.) starts by rallying its 14 veteran contenders in the even more evocative setting of the 2,000-year-old Egyptian Temple of Dendur at the Metropolitan Museum of Art.

There, grandly, Trump receives such returning players as Gary Busey, Stephen Baldwin, LaToya Jackson and reality mean queen Omarosa.

Soon, teammates are chosen by team leaders Bret Michaels and Trace Adkins. Their first assignment: concoct a winning recipe for meatballs, then sell more of them than the rival team.

This is the 13th edition of the Apprentice franchise. “I could probably do another show when I don’t enjoy The Apprentice anymore,” says the 66-year-old Trump, mulling his TV future. “I have been asked by virtually every network on television to do a show for them. But there’s something to sticking with what you have: This is a good formula. It works.”

Trump has the Midas touch, even seemingly profiting from the harsh attention focused on his hair.

“It’s not a wig!” he says, lifting the flaxen locks that flop above his forehead to reveal, plain as day, a normal hairline.

“I wash my hair, I comb it, I set it and I spray it,” he says. “That’s it. I could comb it back, and I’d look OK. But I’ve combed it this way for my whole life. It’s become almost a trademark. And I think NBC would be very unhappy if I combed it back, ’cause — you know what? — maybe I wouldn’t get as high a rating.”