def get_prime_factors(num: int = 600851475143) -> list:
    """Get prime factor(s) of a number.

    Args:
        num (int, optional): the number, for which the prime factor(s) is to be found.
            Defaults to 600851475143.

    Returns:
        list: list of prime factor(s).
    """
    prime_factors: list = []
    sqrt_of_num = num ** (1 / 2)
    for divider in range(2, round(sqrt_of_num) + 1, 1):
        while num % divider == 0:
            prime_factors.append(divider)
            num = num // divider

    if num != 1:
        prime_factors.append(num)

    return prime_factors