In everyday life, we count things using positive whole numbers like 1, 2, 3, 4, 5…

Math nerds like me call these **natural numbers**.

A **prime number** is a particular type of natural number.

*Every natural number greater than 1 is either prime or composite.*

The blue squares below represent every prime number between 2 and 100.

To answer today’s question about whether two is prime, we can check the table above.

**Yes, two is a prime number.** That’s because two’s only factors are 1 and 2.

To explain the difference between prime and composite numbers, we need to understand **factors**.

“Factors” are numbers that can be multiplied together to compose larger numbers.

For example, 2 and 3 are both factors of 6 because they divide evenly into 6.

Six is **not prime** because its factors are 1, 2, 3, and 6.

**We call six a composite number because more than two factors compose it.**

In contrast, **a prime number has only two factors: 1 and itself.**

Take 7 for instance. Seven is prime because its only factors are 1 and 7.

…….

Are you ready for a fun fact? I hope you’re sitting down because this is big!

**Two is the only even prime number!**

Every other even natural number (4, 6, 8, 10…) includes at least three factors: 1, 2, and itself. Therefore, besides the number two, only *odd** numbers* can be prime numbers.

The **largest known prime number** is 2^77,232,917 − 1, a number with 23,249,425 digits. It was discovered just last year by the Great Internet Mersenne Prime Search.

Euclid proved that **there is ****no largest prime number**. Still, mathematicians and enthusiasts continue the search today.

Do you have a favorite prime number? 79 is my personal favorite.