**The factors of 20 are one, two, four, five, 10, 20, negative one, negative two, negative four, negative five, -10 and -20.** The prime factors of 20 are two, four and five.

The factors are the numbers multiplied together to get a certain number. For instance, one and 20 are multiplied together to get 20. Similarly, negative four and negative five can be multiplied together to reach 20 because multiplying two negative numbers makes a positive number. The prime factors are the most basic prime numbers that can be multiplied together to reach a number. In this case, two times two is equal to four, and four multiplied by five is 20.