The number 27 is not a prime number because it is evenly divisibleÂ by 1, 3, 9 and 27. A prime number is a number only divisible by 1 and the number itself. Since 27 is divisible by other numbers, it is considered a composite number.
The number 2 is a prime number. It is the smallest prime number and the only even number that is prime. Its only two factors are 1 and 2.
The number one is neither prime nor composite. Prime numbers are those defined as natural numbers greater than one not divisible by any other numbers but one and itself. Composite numbers have at least one additional positive divisor and include all whole numbers greate...
Two is a prime number. Two is the smallest prime number and the only even prime number, since all other even numbers divide by two.
One is not a prime number because the definition of a prime number is any number that is greater than one that is only divisible by one and itself. Since one is of course not greater than one, it does not fit the definition of a prime number.
Fifteen is not a prime number. A prime number is a positive number that has only two possible divisors, 1 and itself. Fifteen can be divided by 3 and 5 as well as 1 and itself.
The number 21 is not a prime number. Prime numbers are numbers greater than one that are evenly divisible by only 1 and themselves. As the number 21 has multiple factors, including 1, 21, 3 and 7, it does not meet the definition of a prime number.