Project Euler - Python - Problem 3

Lots of work! Not much personal time =) Still working on python!

from math import sqrt

def primenum(num):

    flag = True

    for i in range(4, int(sqrt(num))):

        if (num%i==0):

            flag = False

    return flag

number, primes = 600851475143, []

for i in range(1000, int(sqrt(number))):

    if number%i == 0:

        if (primenum(i) == True):

            primes.append(i)

print(primes)