Is 87 a prime number?
2026-02-28 17:21 Diff
https://brightchamps.com/en-us/math/numbers/is-87-a-prime-number

396 Learners

Last updated on August 5, 2025

The numbers that are categorized on the basis of their number of factors is a prime number. Prime numbers do not have more than two factors Prime numbers are used in cybersecurity and in writing codes for software.

Why is 87, not, a Prime Number?

87 is not a prime number as it has more than two factors, which divides 87 without leaving any remainder. The factors of 87 are 1, 3, 29 and 87. There are various methods to examine if a number is a prime number or a composite number.

Types of methods to find if a number is prime or composite.

  • Counting divisors method
  • Divisibility method
  • Prime number chart method
  • Prime factorization method

Using the Counting Divisors Method

In the counting method, the divisors of the number are counted.

87 has 4 divisors, thus 87 cannot be a prime number as it does not satisfy the two-factor rule.

  • The divisors of 87 = 1, 3, 29, and 87. 


Therefore, 87 is not a prime number. 
 

Using the Divisibility Test Method

The divisibility method states that if a number is divisible by numbers more than two, then the number is not a prime number. The number 87 is divisible by 1, 3, 29, and 87 which makes it a composite number.
 

Explore Our Programs

Using Prime Number Chart

The chart of prime numbers is referred to in this method. The number 87 is checked whether it appears in the chart of prime numbers from 1 to 100.


The prime numbers 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.


By referring to the list, it is understood that 87 does not appear in the list. Therefore, 87 is not a prime number.
 

Using the Prime Factorization Method

The method of writing the number as a product of primes is the prime factorization method. 


The prime factorization of 87 is,


87 = 31 × 291


Therefore, the prime factors of 87 are 3 and 29.
 

Common Mistakes to Avoid When Determining if 87 is a Prime Number.

Students while learning the prime numbers may get confused between prime numbers and composite numbers. The list of prime numbers is a long list and remembering them may be difficult for the students. The mistakes given below will help you identify those areas.
 

FAQs for “Is 87 a Prime Number”?

1. What are the factors of 87?

1, 3, 29, and 87 are the factors of 87.
 

2.Is 87 a composite number?

Yes, 87 is a composite number.
 

3. What are the 5 multiples of 87?

87, 174, 261, 348, and 435 are the first five multiples of 87.
 

4.Is 87 divisible by 3?

Yes, 87 is divisible by 3. 87 ÷ 3 = 29.
 

5.Is 87 divisible by 21?

No, 87 is not divisible by 21 as it leaves a remainder. 87 ÷ 21 = 4.143.
 

Important Glossaries for "Is 87 a Prime Number"

  • Prime Number: The number that has only two divisors, 1 and the number itself.
  • Composite Number: Composite numbers are numbers that have more than two factors.
  • Prime Factorization: Prime factorization is a method of writing all numbers as a product of prime.
     

What Are Prime Numbers? 🔢✨ | Easy Tricks & 🎯 Fun Learning for Kids | ✨BrightCHAMPS Math

▶

Hiralee Lalitkumar Makwana

About the Author

Hiralee Lalitkumar Makwana has almost two years of teaching experience. She is a number ninja as she loves numbers. Her interest in numbers can be seen in the way she cracks math puzzles and hidden patterns.

Fun Fact

: She loves to read number jokes and games.