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.
They are 13 and 19 which are prime numbers
19
23 Prime numbers are odd numbers and 21=3x7
21 is the product of two prime numbers, three and seven. A prime number is defined as a number divisible only by one or itself. So ... NO ... 21 is not a prime number.
19 is 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.
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.
They are 13 and 19 which are prime numbers
19
21 isn't because 7*3=21.
3 x 3 = 9 (Not a prime ; Composite) 1 x 19 = 19 ( Prime) 3 x 7 = 21 (Note a prime: Composite) 5 x 5 = 25 (Not a prime ; Composite).
19 is prime number. 10, 21 and 62 are composite numbers.
23 Prime numbers are odd numbers and 21=3x7
21 is the product of two prime numbers, three and seven. A prime number is defined as a number divisible only by one or itself. So ... NO ... 21 is not a prime number.
3, 7, and 19 have only two factors, 1 and itself. They are prime numbers. 21 has more than 2 factors: 1, 3, 7, and 21. It is a composite number.
One is prime, the other two are composite.