For numbers larger than what can be stored in your computer's native
integer types, you should use an extended precision math library. NTL
is one such option. It provides a type called ZZ which supports
integer operations where the size is limited only by your computer's
memory and speed.
Don
On
Trial division is fine for small numbers, perhaps up to 10 digits. But
think for a moment about what that would take for a 1000 digit number.
The square root of such a number is 500 digits. There are about 10^496
primes smaller than 10^500. If you have a billion computers each
checking a billion of
