The number 4 is classified as a composite number because it has more than two positive divisors. Specifically, the divisors of 4 are 1, 2, and 4. This means that 4 can be divided evenly by these numbers, unlike prime numbers, which have only two divisors: 1 and themselves. In addition to being a composite number, 4 is also the square of 2, as 2 multiplied by itself equals 4. This relationship makes 4 significant in mathematics, particularly in geometry, where it represents the number of sides in a square or a quadrilateral.