max_prime_factor

max_prime_factor.py

import math


def is_prime(n):
    return not [i for i in range(2, int(math.sqrt(n)) + 1) if n % i == 0]


def max_prime_factors(n):
    x = [i for i in range(2, int(math.sqrt(n)) + 1)
         if is_prime(i) and n % i == 0]
    y = [n / i for i in x if i not in x and is_prime(n / i)]
    if not sum([x, y], []):
        return -1
    else:
        return max(sum([x, y], []))


answer = max_prime_factors(600851475143)

print(answer)