Project Euler 3 - Largest even factor

'''
The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
'''

def isPrime(n):
    flag = True
    for i in range(2, int(n/2)):
        if n % i == 0:
            flag = False
            break
    return flag

# MAIN FUNCTION
N = 600851475143
factors = []
for i in range(2, int(N/2)):
    if N % i == 0 and isPrime(i):
        factors.append(i)

print(factors[len(factors)-1])