public static function dec2big(string $number): string
    {
    	static::checkExtensionOrFail();

        $alphabet = static::NUMBERS;
        $number = trim((string)$number);

        if (strlen($number) == 0) {
            throw new Exception('Got empty number for dec2big, can not proceed');
        }

        $mod = (string)count($alphabet);
        $s = '';

        do {
            $x = bcdiv($number, $mod, 0);
            $left = bcmod($number, $mod);
            $char = $alphabet[$left];
            $s = $char . $s;

            $number = $x;
        } while ($x != '0');

        return $s;
    }