What number is a factor of 20 but not a multiple of 4?

A factor of 20 is a number that divides evenly into 20 without leaving a remainder. The factors of 20 are 1, 2, 4, 5, 10, and 20. Among these, the number 5 is a factor of 20 but not a multiple of 4 because it does not result from multiplying 4 by any integer.