using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string someDouble = "1,591,86.4";

        float result;

        float.TryParse(someDouble, NumberStyles.Any, CultureInfo.CurrentCulture, out result);

        //int someInt = Int32.Parse(someDouble);

        //Int64.Parse(someInt.ToString());

        (result * (-1)).ToString();

        someDouble = result.ToString();

​

        Console.WriteLine("{0}", someDouble);

    }

}