Here are examples: https://asecuritysite.com/log/rsa_examples.pdf

Select p and q

N= p x q

PHI = (p-1) x (q-1)

e should not share a factor with PHI.

(d x e) mod PHI= 1 (use inverse mod of PHI here or if simple just loop to find d)

Public key (e,N)

Private key (d,N)

Here is inverse mod N: https://asecuritysite.com/encryption/inversemod

And an introduction to RSA: https://www.youtube.com/watch?v=pHES8eNor6k

You are really going to struggle with 64-bit values, as you values will quick over run this.