using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string batchSubString = "Exception BatchID 25: jfkdlafjdla 34  dfsahfk";

        Regex reg = new Regex(@"(\d+)");

        string batchID = reg.Split(batchSubString)[1];

        Console.WriteLine(batchID);

​

    }

}