CREATE TABLE table_name_98 (pick VARCHAR(255), college VARCHAR(255), round VARCHAR(255), position VARCHAR(255), overall VARCHAR(255))
What is the total number of Pick, when Position is OT, when Overall is greater than 91, when Round is greater than 21, and when College is Mississippi?
    
SQL: SELECT COUNT(pick) FROM table_name_98 WHERE position = "ot" AND overall > 91 AND round > 21 AND college = "mississippi"