在python中查找质数位数之和

def is_prime(num):
    if num < 2:
        return False
    for i in range(2, int(num**0.5) + 1):
        if num % i == 0:
            return False
    return True

def prime_digit_sum(num):
    digit_sum = 0
    for digit in str(num):
        if is_prime(int(digit)):
            digit_sum += int(digit)
    return digit_sum

number = 123456789
sum_of_prime_digits = prime_digit_sum(number)
print("质数位数之和为:", sum_of_prime_digits)