It is: 21 because it has more than two factors
The numbers 13 and 29 are prime - the one composite number in that list is 27.
27 is not a prime number.
29 is a prime. 9, 21, and 27 are composites because they are multiples of 3.
21 is not a prime number because it is 3 x 7
29 is prime.
27
There is an infinite number of prime numbers that are greater than 21. The next prime number after 21 is 23.
39 is not a prime number. It can be divided by 3 and 13.
prime numbers above 13 = 17, 19, 23, 29, 31,...
From 10 to 30, there are 21 numbers.Six of them are prime numbers: 11, 13, 17, 19, 23, and 29.If you pick a number at random from 10 to 30, the probabilitythat it's a prime number is6/21 = 2/7 = 28.57% (rounded)
27
A prime number is a number that is divisible only by 1 and itself; it has no other factors. The factors of 7 are 1 and 7. The factors of 13 are 1 and 13. The factors of 27 are 1, 3, 9, and 27. The factors of 29 are 1 and 29. Therefore, 27 is the only one that is not a prime number.