Number of Style for Image Added into Post

I’m not sure if I understand your question correctly, but…

In WP any attachment is a post (of attachment type). So 3109 is ID of that post.

This means, that if you’ll take a look at wp_posts table, then you should find that post and there should be some additional info stored as meta fields in wp_postmeta table (for example sizes of all generated images are stored as meta).

So the ID of next uploaded image will be the next value of ID column in wp_posts table.