申論題

3.(20%) A sum-product number in a given number base b is a natural number that is equal to the product of the sum of its digits and the product of its digits. For example, the number ]44 in base 10 is a sum- -product numbet, because 1 + 4 + 4= 9, (1)(4)(4) = 16, and (9) (16)= 144. Please implement a function is_ sum product_ number (x) to check whether a natural number x is a sum-product number in base 10.