using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        var cultureInfo = new CultureInfo("pt-BR");

        cultureInfo.NumberFormat.CurrencySymbol = "R$";

​

        CultureInfo.DefaultThreadCurrentCulture = cultureInfo;

        CultureInfo.DefaultThreadCurrentUICulture = cultureInfo;

        var valor = 27500M;

        Console.WriteLine(valor.ToString("N2"));

    }

}