**In mathematics, a factor of a base number is any number that can be evenly divided into the base number.** Due to this definition, a factor can only be less or equal to the original base number. Although all whole numbers can be divided evenly by one, it is still considered a factor.

A single number can have multiple factors. For example, the number 10 has the factors 1, 2, 5 and 10. If a number only has two factors, one and itself, it is considered a prime number. An example of a prime number is 11, which can only be evenly divided by one and 11.