(Prime Strings challenge) How do I make this code work for Strings with more than 5 characters?

Question

I wrote this code hoping to it would work for any String, but it doesn't for some reason. Could someone pinpoint the problem and explain it to make this code work?

https://code.sololearn.com/c5j3ANQQQOgr/?ref=app

Answer 1

https://code.sololearn.com/cKhTn35ncrTi/?ref=app
I made a code to do that.