Adv2015/D20.2/Program.cs

using System;

namespace D20._2
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) throw new ArgumentException();
            var input = int.Parse(args[0]);

            int max = input / 11;
            int test = 0;

            while (test < max)
            {
                var result = SumOfDivisors(test) * 11;
                if (result >= input) break;
                test++;
            }

            Console.WriteLine($"The answer is : {test}");
        }

        private static int SumOfDivisors(int number)
        {
            int result = 0;
            int sqrt = (int)Math.Sqrt(number) + 1;

            for (int divisor = 1; divisor <= 50; divisor++)
                if (number % divisor == 0) result += divisor + number / divisor;
            return result;
        }
    }
}