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23 is prime. 21 is composite as it is 7x3. A Prime number has only 2 factors which are 1 and itself. Composite numbers are every other positive integer except 1 and 0. 1 and 0 are neither prime, nor composite.

Q: Is 23 or 21 composite

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21 is composite. 19 and 23 are prime.

No, they are three numbers, not one. 21 is composite.

21, 55, 77, and 93 are composite numbers. 23 is a prime.

19 is a prime number. Its only factors are 1 and 19. 21 is a composite number. Its factors are 1, 3, 7, and 21. 23 is a prime number. Its only factors are 1 and 23.

17, 19, 23, 29 and 31 are prime. 15, 21, 25 and 27 are composite..

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21 is composite. 19 and 23 are prime.

21 is composite.

No, they are three numbers, not one. 21 is composite.

21, 55, 77, and 93 are composite numbers. 23 is a prime.

19 is a prime number. Its only factors are 1 and 19. 21 is a composite number. Its factors are 1, 3, 7, and 21. 23 is a prime number. Its only factors are 1 and 23.

All the numbers are composite except the ones in bold: 18 19 20 21 22 23 24 25.

17, 19, 23, 29 and 31 are prime. 15, 21, 25 and 27 are composite..

Some are, some are not.

21 is composite.

The only composite factor of 21 is 21.

The composite numbers from 1 to 23 are 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, and 22.

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.