public static function encode($number)
    {
        if (!is_numeric($number)) {
            throw new \RuntimeException("Specified number '{$number}' is not numeric");
        }

        if (!$number) {
            return 0;
        }

        $response = array();
        while ($number) {
            $remainder = $number % 32;
            $number = (int) ($number/32);
            $response[] = static::$symbols[$remainder];
        }

        return implode('', array_reverse($response));
    }