"""The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143?"""

def primes(num):
    x = 2
    primes_list
    if num % x == 0:
        num / x

primes(26)

index = 2
while index is < (number ** (1/2)):
    if you divide number by index and get a remainder of 0, 
    divide the number by index
    this will result
