How to save result in txt file after number has been generated

How to save result in txt file after number has been generated?

from random import randint

def random_with_N_digits(n):
    range_start = 10**(n-1)
    range_end = (10**n)-1
    return randint(range_start, range_end)

for mciNumbers in range(0,1000):
    print('+12129', random_with_N_digits(6))