[zeugma]

I've run a GIMPS client for a while. The numbers are so huge now though, that it takes weeks if not months to test a single number. Personally, I think it's astounding that they can factor a number like 2^74207281-1. That number is so large that it is pretty much imaginary. There is nothing in the universe that there is that many of.

I wish my drivers license or SSN were prime. Sadly, they are both divisable by 2. Yup.I'm a nerd.

[Slicksadick]

Never had I thought to check, but my SS# is prime. Are there many 9 digit prime #s?

[AdmSmith]

Fortunately, no full factorization is needed, just a small test factorization up to about 40 000, then the Pollard's (P-1) method and finally Lucas-Lehmer Primality Testing. It is explained here http://www.mersenne.org/various/math.php

But, it is truly amazing.