Prime factorization of large numbers [closed]

Answer 1

A better algorithm might be the following for searching for primes (my java is rusty, so some tweaking will probably be needed to get it to compile).

if (number % 2)
   factors.append(2)
if (number % 3)
   factors.append(3)

for(int n = 0; n < sqrt(number)/6; n++)
{
   if (number % (6 * n + 1))
      factors.append(6 * n + 1);
   if (number % (6 * n - 1))
      factors.append(6 * n - 1);
}