How many different cats are there in Neko Android?

In Neko Android, you can lure cats to your phone by leaving something to eat on a dish.

I've caught a few cats this way.

I noticed I've caught the same few cats multiple times.

How many cats are there?

And how can I catch them all?

A reddit user called soulctcher got interested in this Easter Egg. He figured out there can be:

[...] a little shy of 10 billion possibilities, although I believe there are MANY codes that will generate visually indistinguishable cats.

His post gives details about the probability of getting cats, waiting time, how to cheat and give yourself more cats, how cats are generated and what is a decent limit of cats before the app starts crashing...

At one point, I put 6000 entries into the file. The app loaded, but scrolling was a complete mess, and I pretty much had to hard reboot the phone after a handful of waits. I then began the tedious process of trying to find a happy limit. I recommend 64 cats at most. You can get away with 128, or even 256 if you're lucky, but you'll definitely suffer through wait messages and poor scrolling.