Why is 639 the sum of all factors of 765, excluding 765?
The factors of the number 765 are: 1, 3, 5, 9, 15, 17, 45, 51, 85, 153, 255, 765.
If you add them up, you will get the total of 1,404. Now subtract 765 to get 639
More numbers for you to try...
Try the
factor calculator