You're looking at the largest prime number ever discovered. That's 257,885,161 – 1, to be exact. If you're looking for the the individual numbers, you'll have to work for it. "Former designer" Philip Bump dissected the prime six digits at a time and converted each chunk into RGB colors. The end result is an image reminiscent of the opening line from William Gibson's Neuromancer. It's weirdly arresting stuff. [Click here to see in hi res]
Like all primes, the newly discovered 257,885,161 – 1 is divisible only by itself and 1. But this prime is special. It's a Mersenne prime — so called because it can be written in the form 2p - 1, where p is also prime. Prime numbers of this form are named after French monk/mathematician Marin Mersenne, who studied them at the beginning of the 17th century.
Searching for Mersenne primes is reportedly among the most efficient ways to look for high primes — a tradition carried on today by number-crunching computers in the Great Internet Mersenne Prime Search, known affectionately as "Gimps." Like Mersenne himself, the people at Gimps study primes not because they are inherently useful, but rather because they are there. Sort of like the Mount Everest of mathematics.
Read more about 257,885,161 – 1 and other Mersenne primes at The Guardian.