SURVIVOR: Caramoan – Fans vs. Favorites” contestant SHERRI BIETHMAN arrived on the island with a big fat secret – she’s stinkin’ rich and doesn’t need the $1 million prize!

The sexy blonde, 41, and her hus­band of 18 years own six fast-food franchises and three homes worth $2 million. But Sherri – one of 20 contenders on the 26th season of the hit CBS series – won’t be blabbing about her bank account, say sources.

“SHERRI IS A BIG ‘Survivor’ fan, so she knows that if you reveal you have money, you’re going to be a target!” a show insid­er said. “Most contestants sign on because they need to win the prize money. So if an actress, professional ath­lete or a previous ‘Survivor’ winner shows up and they’re recognized, it’s over before they can get comfortable!”

Sherri and her husband live in Boise, Idaho, with their 11-year-old son, who’s autistic. The couple owns two Wetzel’s Pretzels franchises, two Jimmy John’s sandwich shops, a Cinnabon, and a Haagen-Dazs. But Sherri says she plans to “totally downplay” the family fortune. “I’m going to say we only own one business and that my husband is an accountant,” the Pilates and cycling fan said in an interview.

Sherri thought about calling her hus­band a banker, she said, “but people would think we had money.”

The source added: “Sherri is going to be very careful who she trusts. The moment her rivals get wind of her fi­nances, they’ll resent her for taking a spot in the tribe from someone who could really use the prize money.

“And it wouldn’t matter if they liked her or not – because most of them are competing to win the $1 million prize for their families. They’d send Sherri packing ASAP, and she wouldn’t even see the backstabbing coming!”