找出指定数字的所有质因数，比如：90=2*3*3*5。

from math import sqrt
from functools import reduce
from operator import mul

def is_prime(n):
    for k in range(2, int(sqrt(n))+1):
        if n % k == 0:
            return False
    return True

def get_prime(num):
    temp = []
    for i in range(2, num+1):
        if num % i == 0 and is_prime(i):
            temp.append(i)
    return temp

def final_factor(num):
    prime_factor = get_prime(num)
    while reduce(mul, prime_factor) < num:
        mid_calc = reduce(mul, prime_factor)
        prime_factor.extend(get_prime(num//mid_calc))
    return sorted(prime_factor)

结果：[2, 3, 3, 5]