A number with more than two factors is called a composite number. A factor is a number that is evenly divisible into another number. Prime numbers, by definition must be larger than one and have only themselves and one as factors.
Any whole number that is not a prime number is a composite. All even numbers, except the number two are composites, as they are divisible by two. Prime factors of a number are useful in finding the least common denominator in a fraction. They are also helpful in determining the greatest common factor of a number. The larger a number, the greater the chance it is a composite.