Whole number that is greater than 1 and that has more than two distinct divisors.
- The number 0 and 1 are not composite numbers.
- The list of composite numbers under 25 is: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24.
Properties
- All composite number can be expressed in a unique way in the form of a product of prime numbers.
15 = 3 × 5
24 = 2 × 2 × 2 × 3
35 = 5 × 7
- A prime number is not a composite number, and vice versa.
Examples
- The number 15 is a composite number because: div(15) = {1, 3, 5, 15}; it has more than two distinct whole divisors.
- The number 13 is not a composite number because it only has two distinct whole divisors: div(13) = {1, 13}.