python生成19位Luhn 算法号码，要求前六位为621621

好的，以下是前六位为621621的Python代码示例：

import random

def luhn_checksum(card_number):
    def digits_of(n):
        return [int(d) for d in str(n)]
    digits = digits_of(card_number)
    odd_digits = digits[-1::-2]
    even_digits = digits[-2::-2]
    checksum = 0
    checksum += sum(odd_digits)
    for d in even_digits:
        checksum += sum(digits_of(d*2))
    return checksum % 10

def is_luhn_valid(card_number):
    return luhn_checksum(card_number) == 0

def generate_card_number(prefix):
    card_number = prefix
    while len(card_number) < 19:
        digit = random.randint(0, 9)
        card_number = card_number + str(digit)
    checksum = luhn_checksum(card_number)
    check_digit = (10 - checksum) % 10
    return card_number + str(check_digit)

prefix = '621621'
card_number = generate_card_number(prefix)
print("生成的19位Luhn算法号码为：", card_number)

该代码会先将前六位设置为"621621"，然后生成随机的13位数字，最后加上校验位得到19位银行卡号。生成的银行卡号会通过Luhn算法校验，保证其合法性。