Another prime number down, infinity to go

There are 17 million digits in the largest prime number we know of, so far. Its discovery is part of an ongoing distributed computing project aimed at exposing the existence of ever larger prime numbers, largely because prime numbers are there — flagrantly going around, only being divisible by themselves and the number 1. We'll show them, won't we? The Electronic Frontier Foundation foundation, for instance, is currently offering a $150,000 bounty for the first folks to bring in a 100-million-digit prime.