Thousands of volunteers, and their computers, have determined the largest prime number found to date -- a 17 million digit number -- a U.S. researcher says.

University of Central Missouri Professor Curtis Cooper, who heads the Great Internet Mersenne Prime Search, or GIMPS, announced the find, CNET reported Wednesday.

A prime number is divisible only by itself and the number 1. Mersenne primes are named after a French monk born in 1588 who described a particular class of prime number, 2 to the power of "p" minus one, in which "p" is an ordinary prime number.

The newly discovered prime is 2 to the power of 57,885,161 minus 1 and is 17,425,170 digits long.

It's the 48th Mersenne prime so far discovered. The GIMPS project has found the 14 largest Mersenne primes.

A $3,000 prize has been awarded to Cooper for the discovery, but prime number hunting could get more lucrative in the future -- the Electronic Frontier Foundation has announced a $150,000 award for the discoverer of the first prime number of 100 million digits or more.

Cooper and his prime-hunting network of volunteers and their computers previously found record primes in 2005 and 2006.