31 and 61 are prime, the rest composite.
Chat with our AI personalities
21 is a composite number because it has more than two factors
21 is a composite number. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.
21 is a composite number. A prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.
27 is composite. 27 = 3 * 3 * 3 = 3315 is composite. 15 = 3 * 521 is composite. 21 = 3 * 723 is a prime number. It is only evenly divisible by itself and one.
21 is a composite number