Is 158 a prime number?

The number 158 has got 4 factors, that are capable of dividing the number completely without leaving any remainder. Thus the number 158 is a non-prime number. The factors of 158 include 1, 2, 79, and 158.

A number to be a prime number should follow the criteria, which is that it should not have factors more than 2. Here, 158 has more than 2 factors, hence making it a composite number.

Given below are a few ways that can be used to find prime or composite numbers.

The different methods we can use to check if a number is a prime number are explained below.

1. Counting Divisors Method
2. Divisibility Test
3. Prime Number Chart
4. Prime Factorization
    

For the counting divisors method, it is to be checked whether the number is divisible by any numbers other than 1 and the number itself.

The counting divisors method for 158 would simply be:

Divisors of 158 = 1, 2, 79, 158
Number of divisors = 4

The number 158 can be considered composite.
 

In the division test, we try to divide the number by any of the prime numbers. If we cannot, then it is considered a prime number.

In the divisibility method, the prime number only has 2 divisors, which are 1 and itself.

Thus, 158 consists of 4 factors that divide it completely without any remainder.
 

The prime number chart is the list of prime numbers starting from 2 to infinity.

The list of prime numbers under 100 are:

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

158 is not present in the list, it is not a prime number.
 

This method is only used for a non-prime number/composite number. Since 158 is a composite number, the prime factorization for 158 is:

Factors of 158 = 2 × 79
 

• Prime Number: A natural number greater than 1 that has only two distinct positive divisors: 1 and itself. For example, 2, 3, 5, and 7 are prime numbers.

• Composite Number: A number that has more than two divisors, meaning it can be divided exactly by numbers other than 1 and itself. 158 is a composite number because it has the divisors 1, 2, 79, and 158.

• Divisibility Test: A method used to check whether a number is divisible by another without performing the division. This test helps determine if a number is prime or composite by checking divisibility by smaller prime numbers like 2, 3, 5, etc.

• Prime Factorization: The process of breaking down a composite number into its prime factors. For 158, the prime factorization is 2 × 79.

• Divisors: The numbers that divide into another number without leaving a remainder. For 158, the divisors are 1, 2, 79, and 158.