Is 16 a prime number?

There are many tests to find if 16 is a prime number or not. But since 16 is a small number, it is easy to test. We can see that 16 has 5 divisors: 1, 2, 4, 8 and 16. But a prime number has only 2. So, 16 is not a prime number.
 

There are several methods to show that 16 is not a prime number. Let us look at these methods and learn them step by step.

One of the easiest methods to find if a number is prime or not is by counting the divisors. We will list all the divisors of 16. If the number has more than 2 divisors, it is a composite number. As we can see, 16 has five factors, making it a composite number. 
 

We will be checking the divisibility of 16 by a set of numbers. If divisible by any of the numbers, 16 is not a prime number.

Divisibility by 2: For a number to be divisible by 2, it has to be an even number. And 16 is an even number. Hence, it is divisible by 2. 

Divisibility by 3: The number should be a multiple of 3 to be divisible by 3. We can see that 16 is a multiple of 3. When we add 6 and 1, we will get an answer of 7. This shows that 16 is not divisible by 3.

Divisibility by 5: 16 is not divisible by 5 as it does not end with 0 or 5.

This shows that 16 is divisible by 2, apart from 1 and 16. Since this violates the rules of a prime number, 16 is not a prime number.
 

First let us look at the prime numbers from 1 to 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97. As we can see, 16 does not appear in the list. This confirms that 16 is not a prime number.
 

Prime factorization helps determine the prime factors of numbers. For instance, 16 is a composite number because it has a prime factor of 2. Indeed, 16 can be presented as 2 × 2 × 2 × 2 = 16, and thus showing it has factors other than 1 and 16. 
 

• Prime Factorization: Prime factorization is one of the operations of a mathematical expression in which a number is expressed as the product of its prime factors. For example, the prime factorization of 6 is 2×3.

• Multiple: It is the number when multiplied to another number, so multiple is the product of two numbers. Like 16, 32, 48, 64, 80 are the multiples of 16.

• Composite numbers: Composite numbers are natural numbers that are greater than 1 and have more than 2 factors other than 1 and itself. Some examples for composite numbers are 4, 6 and 9.

• Whole Numbers: If a number is an integer, and it has no fraction then it is called a whole number. Some examples for whole numbers are 1, 2, 3, 4, 5 and so on.