What is a Composite Number?

As discussed above, Composite numbers are those numbers that have two or more factors. However, most of the numbers have two or more factors making them fall into the category of Composite numbers. All the natural numbers which are not prime numbers are Composite numbers.

For example – 4 is a Composite number as it gets divided by 1,2, 

and 4. Now we take 17; its factors are 1 and 17 itself, which means it’s a prime number; therefore, 17 is not a Composite number.

We Will further read in-depth about the composite number and the smallest composite number. 

Composite Number

Definition

Composite Numbers are those numbers that have more than two factors dividing the number. Composite numbers are the opposite of Prime numbers divisible by only two numbers/factors, i.e. one and the number itself. 

An even number greater than 2 is always a composite number. Which means it will always be divisible by two or more numbers.

Can zero be considered a composite number?

Zero can neither be a composite nor a prime number as it does not have any factors of its own.

Example of Composite number

Properties of Composite Numbers

• Numbers having two or more factors are called Composite numbers.

• These numbers are evenly divisible by their factors

• One of the factors of a Composite number is the number itself

• 4 is the Smallest Composite Number

• Every composite number has at least two prime numbers as it’s a factor  (Eg. 63= 7 x 9, where 7 and 9 are prime numbers)

• Composite numbers are divisible by other composite numbers

Composite Numbers, how to analyse?

To analyse a number to be a composite number,  first, find out how many factors that number has?

If the factor of a number is more than two, then it’s a Composite Number.

Divisibility test for Composite Numbers

Divisibility test is done to find whether the number has three or more factors. When a number is divided by another number completely, and zero is the remainder, then it is known to be its factor, and this test is known as the visibility test. 

Let’s see if the following numbers have any common factors: 4,16,25,35, 44, and 50 

• If the given number is even, start checking with the number 2

• If the number ends with a 0 or 5, check it by 5.

• If the number cannot be divided by any of these given numbers, then the number is a prime number

• For example, 88 is divisible by 2, which means it has factors other than 1 and 88, so we can say 68 is a composite number

Types of Composite Numbers

• Odd Composite Numbers

• Even Composite Numbers

Odd Composite Numbers

All non-prime odd numbers are called Odd Composite Numbers. For example, 33, 35, 39, 49, 51, 55, are odd composite numbers. Let’s take 1, 2, 3, 4, 9, 10, 11, 12 and 15. Here 9 and 15 are the odd composites because these two numbers have odd divisors, and they fulfil the condition of composite numbers. 

Even Composite Numbers

What are Even Composite Numbers?

Even numbers that are not prime numbers are termed Even Composite Numbers. For example, 34,36, 38, 40, 42 are even numbers, and none are prime numbers; hence they are all Even composite Numbers. Let’s take another example: 

1,4,9, 16, 25, 36, 49, 64, 81, 100.

Here 4, 16, 36, 64, 100 are the even composites because they fulfil all the conditions of Even Composite Numbers.

Smallest Composite Number

When a natural number is divisible by more than two numbers, we term it Composite Numbers. Let’s understand it with an example. Now, as we start counting: 1, 2, 3, 4, 5, 6,.. so on, it is noticed that 1 cannot be a composite number as it is its own divisor. Neither can two be a composite number as it has only two divisions. 3 again has only two factors 1 and 3, so it’s not a composite number.

 Now arriving at 4 , it has more than 2 factors – (1, 2, 4) and thus 4 satisfies all the conditions of a composite number.. So, 4 is the smallest composite number

Conclusion 

Hence, let’s conclude by recapping the content so far.

What is a composite number?

Composite numbers are those numbers that have two or more factors. However, most of the numbers have two or more factors making them fall into the category of Composite numbers. All the natural numbers which are not prime numbers are Composite numbers.

There are two types of composite numbers: even and odd Composite number

four is considered the smallest composite number. Every composite number has at least two prime numbers as its factor. After reading this article, I hope all the concepts related to composite numbers will be clear.