Use CultureInfo int ToString method

   
 


using System;
using System.Globalization;
using System.Threading;

class Program {
    static void Main(string[] args) {
        int val = 1234567890;
        Console.WriteLine(val.ToString("N"));
        Console.WriteLine(val.ToString("N",new CultureInfo("fr-FR")));
        Thread.CurrentThread.CurrentCulture = new CultureInfo("de-DE");
        Console.WriteLine(val.ToString("N"));
    }
}