Q: What is the sum of all factors of the number 1,989 excluding 1,989?
A: 1,287
The factors of the number 1,989 are: 1, 3, 9, 13, 17, 39, 51, 117, 153, 221, 663, 1989.
If you add them up, you will get the total of 1,990. Now subtract 1,989 to get 1,287