21 is a dramatic film about MIT students who count cards and win millions of dollars from Las Vegas casinos. The film is loosely based on the book Bringing Down the House by Ben Mezrich. In the book, Mezrich and other students dubbed the MIT Blackjack Team are financed by a man named Micky Rosa to win millions of dollars at Las Vegas casinos.

The film was helmed by director Robert Luketic, whose previous films include Legally Blonde and Monster-In-Law. It received mostly negative reviews, scoring 31% on Rotten Tomatoes. Critic Bryant Frazier said "Harold & Kumar Go to Las Vegas would be lots more fun as well as more sociologically astute."