Euler #69

def prime(n):
    if n == 2 or n == 3: return True
    if n < 2 or n % 2 == 0: return False
    if n < 9: return True
    if n % 3 == 0: return False
    r = int(n**0.5)
    f = 5
    while f <= r:
        if n % f == 0: return False
        if n % (f+2) == 0: return False
        f += 6
    return True

primes, product, index = [], 1, 0
for x in range(500001):
    if prime(x):
        primes.append(x)

while product < 10**6:
    product *= primes[index]
    if product > 10**6:
        print(product/primes[index])
        quit()
    index += 1
print(product)