Couple useful speedups for your loop: you only need the xrange to go up to floor of sqrt(p), since any divisor would have been found already by that point. Also

Couple useful speedups for your loop: you only need the xrange to go up to floor of sqrt(p), since any divisor would have been found already by that point. Also you can save a lot of divisions by working as a sieve with the first couple thousand primes (so check divisibility against a store list of primes, instead of all numbers, for as long as your memory allows).