What is the sum of the factors of 21?

Let's break down what this question is asking.

It wants the sum of, meaning the value added together, of the factors of, meaning the whole numbers that you can divide into 21 and still get a whole number, 21.

Let's see what the factors of 21 are:

Well, 21= 121, 21=37, and that's it!

Now to sum them up, 1+3+7+21 = 32. So the answer here is 32.