2 is not a composite number because it has only two factors. Since 2 is divisible by only 1 and itself, therefore, it cannot be considered as a composite number because the criteria for a number to be called composite is that it should have more than 2 factors, that is, 1 and the number itself. Thus, 2 is a prime number, according to which a number is said to be prime if it has only 2 factors, that is, 1 and the number itself, for example, 2.