Calculate Additive Persistence of a Number in Python

Enter number: 14159
9, 5, 1, 4, 1,

def persistence(num: int):
    """
    Finds the persistence of a number.
    """

    RADIX = 10

    num = abs(num)
    ctr = 0
    while num != 0:
        unit = num % RADIX
        num //= RADIX
        num = unit * RADIX + num
        ctr += 1

    return ctr


def digit_sum(num: int):
    """
    Finds the sum of the digits of a number.
    """

    RADIX = 10

    num = abs(num)
    sum = 0
    while num != 0:
        digit = num % RADIX
        sum += digit
        num //= RADIX

    return sum


def main():
    """
    Finds the persistence of a number.
    """

    num = int(input("Enter number: "))
    print(persistence(num))