In this tutorial, you will learn what is a prime number and how to check whether the given number is a prime number or not using PHP.

### What is Prime Number?

A prime number is a natural number which is exactly two positive divisors, 1 and itself. For example, take number 13, its a prime number because it has only two positive divisors.

### How to Check Prime Number with PHP?

### Below is the simple PHP program to find a given number is prime or not using for loop and if..else control structure.

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<?php function IsPrime($n) { for($x=2; $x<$n; $x++) { if($n % $x ==0) { return false;} } return true; } $a = IsPrime(13); echo $a ? 'This is a Prime Number.' : 'This is not a Prime Number.'; ?> |

### Output

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This is a Prime Number. |

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