# Prime Numbers Definition

The **prime number** is the one that has only **two** factors i.e. **1 **and the **number** itself. In simple **words**, we can say a number that **can’t be divided by any other number** completely is said to be **Prime Number**. It can have a maximum of **two factors** on this page.

**Note:**

You can read about Factors here.

**Table of Contents**

- Terms related to Prime Numbers
- How to check if a number is prime or not?
- Fun Facts of Prime Numbers
- FAQ's

It is also **considered** the opposite of **Composite numbers** (Numbers with at least three factors). **For example**, 7 is the prime number because it can’t be **divided** by any other number with **0** remainders left.

**Note:**

Read about Composite Numbers here.

**Prime Numbers less than 30.**

3, 5, 7, 11, 13, 17, 19, 23, 29.

## Terms related to Prime Numbers

There are **two** main terms related to **Prime Numbers** that we are going to **mention** here.

**Co-Prime**: Two numbers that have only**one common factor**i.e. “1”. For example,**9 and 10**are**prime numbers**because they have**1**as their**common**factor only.**Twin Prime**: The**pair**of prime**numbers**is called a**Twin Prime**if it has only**one composite number**between them.**For example**,**(3, 5),****(11, 13),**and**(5, 7)**are**Twin Primes**because they have only one**composite**number between them.

### How to check if a number is prime or not?

You can **easily** find if the given **number** is prime or **not** just by **dividing** it by different **terms**. If a number is **divisible** by any other number except **1** and by the **number** itself, it is not called a **Prime Number**.

**Example 1:**

Check whether **16** is a prime number or not.

**Solution:**

Let us divide **16** with different prime numbers less than **16**.

**16**is divisible by**2, 4,**and**8**.

It shows that **16** is not a Prime number because it has **3 **more factors except 1..

**Example 1:**

Check whether 31 is a Prime number.

**Solution:**

By using our division testing, we have found that **31** is not divisible by **any whole number**. That is why **31** is termed to be a Prime Number.

### Fun Facts of Sum

**2**is the smallest**prime number**.- The only
**even number**that is**prime**too is “**2**”. **2**&**3**are only consecutive**prime numbers**.**0**&**1**is neither a**prime**nor a**composite**number.- All numbers
**ending**with**5**except**5**can’t be**prime numbers**. - The
**occurrence**of prime numbers reduces with the**increase**in value.

### FAQ's

**Is 1 a Prime number?**

No, 1 is neither a prime number nor a composite number. It is part of the Natural and Whole number set only.

**What is the smallest prime number?**

“2” is the smallest prime number.

**Are all odd numbers prime?**

No, odd numbers can be prime or composite. But all even numbers except 2 are composite numbers.

**Can a prime number be negative?**

No, a prime number can’t be negative. It is called an Integer only instead of giving any other name.

**What is the difference between prime numbers and composite numbers?**

Prime numbers have only two factors including 1 while Composite numbers have at least three factors including 1.