Quote Originally Posted by laserlight
You could give the GMP library a try.


GMP:

Quote Originally Posted by http://www.swox.com/gmp/guestaccount.html
People sometimes offer us accounts on Windows machines; unfortunately, that isn't useful since we don't develop GMP for such arcane platforms.
Hmm...



I also made a prime calculator once, but it stuck to the 2^32-1 limit. You can make your own simple class (struct if you use C) to handle bigger numbers, though.