Mine

def is_prime(n):        if n < 3:        return False #too small/negative        if n%2 == 0:        return False #even        for i in range(3, int(n**0.5)+1, 2):            if n%i == 0:            return False            return True        def check_prime_factors(n, prime_list):    for prime in prime_list:        if prime < n and n%prime == 0:            return prime         prime_list = []for n in range(1000000):    if is_prime(n):        prime_list.append(n)prime_list.reverse()print "done making list"print check_prime_factors(600851475143, prime_list)