UCLA mathematicians appear to have won a $100,000 prize from the Electronic Frontier Foundation for discovering a 13-million-digit prime number that has long been sought by computer users.

While the prize money is nothing special, the bragging rights for discovering the 46th known Mersenne prime are huge.

"We're delighted," said UCLA's Edson Smith, leader of the effort. "Now we're looking for the next one, despite the odds," which are thought to be about one in 150,000 that any number tested will be a Mersenne prime.

Prime numbers are those, like three, seven and 11, that are divisible only by themselves and one. Mersenne primes, named after the 17th century French mathematician Marin Mersenne, who discovered them, take the form 2P - 1, where P is also a prime number.

In the new UCLA prime, P = 43,112,609.

Thousands of people around the world have been participating in the Great Internet Mersenne Prime Search, or GIMPS, in which underused computing power is harnessed to perform the complex and tedious calculations needed to find Mersenne primes. The prize is being offered for finding the first Mersenne prime with more than 10 million digits.