Player rating for tournaments across all installments of Heroes.

Rp=50(N-n+1+b/N+b)^2
For first place, Rp=50*(21-1+1+3/21+3)^2=29144 (since ^2 means squaring).
What do I think is wrong?

Apparently, this was my mistake. I meant (N-n+1+b)/(N+b), and all of that squared. From a formal mathematical notation standpoint, you were absolutely right, but I couldn't have imagined that the notation would be interpreted differently. That's why the misunderstanding arose. Now everything has been corrected. It's good that this question came up right away.

That is, we won't be calculating from a base of 100 points? Because after multiplying the rating of all participants by some number, we should again bring it to a hundred-point system...

The 100-point system is the base rating, but the final rating awarded for the tournament can be higher or lower. This is the simplest and most accurate way to show the difference between a serious tournament and a warm-up. Awarding 100 points to both the winner of the Grand Tournament and the winner of a small, informal competition is not right.