Withing the media folder (site files) each media file has a bath like so:

\media\12345\file_name.pdf

What does the id in bold represent? It's not the media object ID (I've checked). I'm creating media objects and uploading the files to the media folder and was wondering how to create the folder name:

Media media = Media.MakeNew(row["fName"].ToString(), MediaType.GetByAlias("File"), author, 3440);
string folderPath = Server.MapPath("/media") + "\\" + media.getProperty("umbracoFile").Id;
string fullPath = folderPath + "\\" + fileName;

Directory.CreateDirectory(folderPath);
File.WriteAllBytes(fullPath, bytes);

media.getProperty("umbracoFile").Value = "/media/" + media.getProperty("umbracoFile").Id + "/" + row["fName"].ToString();
media.getProperty("umbracoExtension").Value = "pdf";
FileInfo fileInfo = new FileInfo(fullPath);
media.getProperty("umbracoBytes").Value = fileInfo.Length;

//link media object to document
doc.getProperty("file").Value = media.getProperty("umbracoFile").Id;