Now I very recently wrote an investigation paper on RSA Encryption and how it works. After completing it, I thought of looking up real life key generators. To my surprise, they all have characters within them, and not just numbers... Everything I've read till now has been based on the fact that RSA works solely on prime numbers + Euler's Totient function + Modular Arithmetic. I know how to encrypt when the public and private keys are solely numbers, but how is it done with characters?

Just to make it clear, I do know how to use RSA encryption and know the math behind it.

PS: Here are a few links :

<https://travistidwell.com/jsencrypt/demo/>

<https://www.devglan.com/online-tools/rsa-encryption-decryption>