PHP Min Perimeter Rectangle
function minPerimeterRectangle(int $n): int
{
    $i   = 1;
    $min = PHP_INT_MAX;
    while ($i * $i < $n) {
        if ($n % $i === 0) {
            $min = min($min, (2 * ($i + $n / $i)));
        }
        $i++;
    }

    return $min;
}

This searches factor pairs up to the square root and picks the pair with the smallest perimeter.