Is 87 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

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. 
 

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.
 

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.
 

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.
 

• 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.