sieve_of_Eratosthenes

def get_primes(limit):#sieve of Eratosthenes
    primes = []#this will hold the primes
    bools = [True for i in range(2, limit + 1)]
    nums = range(2, limit + 1)
    for i in range(2, (int(limit**0.5)) + 1):
        if bools[i]:
            j = i**2
            while j <= limit:
                bools[j-2] = False
                j += i
    for i in range(len(bools)):
        if bools[i] and nums[i]**0.5 != int(nums[i]**0.5):
            primes.append(nums[i])
    return primes

def prime_fac(num, unique=False):#get unique prime factors
    prime_divs = []
    primes = get_primes(num)
    for prime in primes:
        while num % prime == 0:
            prime_divs.append(prime)
            num /= prime
    if unique:
        return set(prime_divs)
    return prime_divs