So I found this question: How much Bitcoin will I mine right now with hardware X?

I’m interested in understanding what exactly are the following values: 65535 and 2^48. I know that the former is concerned with 16 bits? And if that is correct, then for the unsigned integer of 16 bit size, you can express 2^16 - 1 values (i.e. we do not count zero), so you get 65535. I do not understand why we plug it into this equation though:

  (H*B/D) * (60*60*24 * 65535 * 10^6 / 2^48) = (H*B/D) * (5.662224e15 / 2^48)              BTC per day (1) 

But I also know that D*((2^48)/65535) is the number of hashes (in Mhash) that you have to solve to find a block.

So the equation that I gave you, I can understand that 60*60*24 is number of seconds in a day. Let’s denote it as S. Then:

(H*B/D) * (S * 10^6 * (65535 / 2^48)) 

So I assume, 10^6 is some kind of hash to Mhash modifier (and that makes sense because 65535/2^48 is inversed, so we have to multiply and not divide).

So my question is, what is 65535 and 2^48. And then what is 2^48/65535 and what is 65535/2^48. Please be technical, but clear. Thank you.