import math


def get_product_factors(n):
    """ get product factors of n
    """
    if n <= 0 or not isinstance(n, int):
        return []
    else:
        product_factors = []
        for i in range(1, math.ceil(math.sqrt(n)) + 1):
            if n % i == 0:
                product_factors.append(i)
                product_factors.append(int(n / i))

        return sorted(list(set(product_factors)))