Find all prime Factors of a given number

def is_prime(num):
    for i in range(2,num):
        if (num % i) == 0:
            return False
    return True

def all_prime(n):
    list = []
    for a in range(2,n):
        if is_prime(a) == True:
            list.append(a)
    return list

n= int(input("enter number: "))
b = all_prime(n)

def prime_factors(n):
    factors = []
    for c in b:
        if n % c == 0:
            factors.append(c)
    return factors

e = prime_factors(n)
print(e)