如何在Python中将整数转换为最短的url-safe字符串？

import base64

def int_to_urlsafe_string(num):
    num_bytes = num.to_bytes((num.bit_length() + 7) // 8, 'big')
    urlsafe_string = base64.urlsafe_b64encode(num_bytes).decode('utf-8')
    return urlsafe_string

num = 123456789
urlsafe_string = int_to_urlsafe_string(num)
print(urlsafe_string)

AQAAAAA