IPhone camera app with auto-numbering on photo?

Is there a camera app that puts auto-numbering on photos (watermark)? I take photos of products in sequence and having a number would greatly help with my paper cataloging. Most products look very similar…

You do have the file name, it just isn't visible on the photo.

When I worked as a product photographer, I made up a little stand and wrote the item's SKU number on it. I then had that number in the frame, but in a position where it was easy to crop it out in post production.