When the "factors" of a number are listed, the list is usually restricted to positive factors. Then there would be no answer to the question, because no group of positive numbers can add up to make zero.
25
what two factors of -21 add up to -6
21, 21, 21, 21 , 15, 1
819
your penis
20 and 21
21
There are 12 different combinations of 3 positive odd numbers that add up to 21. Namely: (There are many permutations of these combinations.) 1,1,9 1,3,17 1,5,15 1,7,13 1,9,11 3,3,15 3,5,13 3,7,11 3,9,9 5,5,11 5,7,9 7,7,7
Numbers are positive unless they have a minus sign (-) in front of them, in which case they are negative. As for the sum of positive and negative numbers, just add them up and find out. Add the positive, subtract the negative. It's very logical.
The numbers are 21, 22, 23, 24, and 25.
59