PHP Code to check if number is prime or not

PHP Code:

<!DOCTYPE html>
<html>
    <head>
        <style>
            input{
                width: 200px;
                font-size: 20px;
                padding: 10px;
                margin: 10px;
            }
        </style>
    </head>
<body>

<h3>Php Code to check if number is prime or not</h2>
<form method="$_GET">
    <input type="number" placeholder="Enter a Number.." name="number" />
    <input type="submit" name="send" />
</form>

<?php
    if (isset($_GET['send'])){
        $number = $_GET['number'];
        $count = 0;
        for ($i = 1; $i <= $number; $i++){
            $res = $number % $i;
            if ($res == 0){
                $count++;
            }
        }
        if ($count < 3){
            echo "<h3>",$number, " Number is Prime</h3>";
        }
        else{
            echo "<h3>",$number, " Number is Not Prime</h3>";
        }
        $count = 0;
        $number = 0;
        $res = 0;
    }
?> 

</body>
</html>

Output: