The number 21 would be the answer. 19 and 23 only have two factors, 1 and themselves, as they are prime numbers. 25 only has 1, 25 and 5. 21 has 1, 21, 3 and 7 for 4 possible factors.
21 = 3 x 7, so it is not a prime number. 23 = 1 x 23, it does not have any other factors, so it is a prime number. 25 = 5 x 5, so it is not a prime number.
21
They are all prime numbers except for 15 21 25 and 27 which are composite numbers
21 22 23 24 which is the prime number
The number 1 is neither prime nor composite. The numbers 25, 16, 21, and 27 are divisible by factors that are not one or the number itself. 19 is the only one that has only 1 and itself as factors, so it is a prime number.
The number 21 would be the answer. 19 and 23 only have two factors, 1 and themselves, as they are prime numbers. 25 only has 1, 25 and 5. 21 has 1, 21, 3 and 7 for 4 possible factors.
None of them is a prime number.
23 is a prime number.
17, 19, 23, 29 and 31 are prime. 15, 21, 25 and 27 are composite..
21 = 3 x 7, so it is not a prime number. 23 = 1 x 23, it does not have any other factors, so it is a prime number. 25 = 5 x 5, so it is not a prime number.
Only 23 is a prime number.
None of them are prime numbers
21
21
They are all prime numbers except for 15 21 25 and 27 which are composite numbers
21 22 23 24 which is the prime number