using System;

using System.Globalization;

using static System.Console;

​

public class Program

{

    public static void Main()

    {

        var comCultura = DateTime.Now.ToString("dd \"de\" MMMM \"de\" yyyy", new CultureInfo("pt-BR"));

        var semCultura = DateTime.Now.ToString("dd \"de\" MMMM \"de\" yyyy");

        WriteLine($"Definindo a cultura: {comCultura}");

        WriteLine($"Sem definir a cultura: {semCultura}");

    }

}