DailyCoding20120725.py

# -*- coding:utf-8 -*-

prime_number = list()

def function(num):
    count = largest = 1
    while num != 1:
        count += 1
        if any([count % x == 0 for x in prime_number]):
            continue
        else:
            prime_number.append(count)
            while num % count == 0:
                num /= count
                largest = count
    return largest

print function(600851475143)