The product of two number is 7168 and their H.C.F. is 16. find the sum of all possible numbers?

Let the number be 16a and 16b, where a and be are two number prime to each other.
∴ 16a x 16b = 7168
∴ ab = 28
Now, the pairs of number whose products is 28, are (28, 1) : (14, 2), (7,4)
14 and 2 which are not prime to each other should be rejected.
Hence, the required answer
= (448 + 16) + (112 + 64) = 640