So is there any way to derive or calculate the number representation from btc address that coresponds to its private key hex?
Ehm, what? No! There's no chance of that actually happening. I mean, unless youve got some crazy powerful supercomputer and a few million years to spare.
The private key and public address are cryptographically linked, but you cant work backwards from one to the other. It is part of what makes Bitcoin so secure.