protected static Long getQForN(int number) {
        if (number < 0) return new Long(-1);
        if (number == 0) return new Long(10);
        if (number == 1) return new Long(1);

        int N = number;
        List<Integer> multipliers = new LinkedList<Integer>();
        for (int i = 9; i > 1; i--) {
            while (N % i == 0) {
                multipliers.add(0, i);
                N = N / i;
            }
        }
        String Q = "";
        for (int i : multipliers) Q += i;
        return (N == 1) ? new Long(Q) : -1;
    }