Here is an easy solution:
def numberToBase(n, b):
    if n == 0:
        return [0]
    digits = []
    while n:
        digits.append(int(n % b))
        n //= b
    return digits[::-1]
So if you need to convert number to the base 577,
numberToBase(67854 ** 15 - 102, 577) then
This will give you a correct solution which is - [4, 473, 131, 96, 431, 285, 524, 486, 28, 23, 16, 82, 292, 538, 149, 25, 41, 483, 100, 517, 131, 28, 0, 435, 197, 264, 455],
Which you can later convert to any base you want based on your requirement.