you can use this code to check OS is 64 bit or 32 bit.

Check 64 bit OS and process

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            bool blIs64BitOS = Environment.Is64BitOperatingSystem;
            if (blIs64BitOS)
                Console.WriteLine("This is a 64bit OS");
            else
                Console.WriteLine("This is a 32bit OS");

            bool blIs64BitProcess = Environment.Is64BitProcess;
            if (blIs64BitProcess)
                Console.WriteLine("This is a 64bit process");
            else
                Console.WriteLine("This is a 32bit process");
        }
    }
}