3 QB, 7 WR, 6 RB, 2 TE, 15 OL. Enough to have 11 players per formation. You could get by with fewer OL and have them play on 2 formations.
11 on D and then another 11 on Sp. Teams.
You may also want backups for key positions (RBs, WRs, DBs, & KRs) so you can swap them out in the second half.