The book Bringing Down the House has long been one of my favorites, so it’s not a huge surprise that Sony’s film adaptation is the film equivalent of a blackjack. Produced by and featuring Academy Award winner Kevin Spacey, 21 has delivered an $8.2M opening day, and Sony will finish the weekend with a stack of chips totaling an estimated $23.39M.

21 is based on Ben Mezrich’s account of the life of a former MIT student and card-counter named Kevin (real name Jeffrey Ma). I met Kevin or Jeffrey soon after the book became a bestseller, and the first time I interviewed him on my ESPN radio show, he didn’t give his name because he still feared for his safety. After all, the guy was part of an operation that won millions of dollars from the casino industry. I talked with Ma on my radio show, The Steve Mason Show, back in February on radio row at Super Bowl 42. This is fascinating stuff. If you’d like to hear the conversation, here’s a link.

The #2 spot for the day and for the weekend goes to Horton Hears a Who (Fox), which will score another nice weekend hold. Horton has cracked the $100M mark with a strong 3rd Friday of $5M, and the CGI animated Dr. Seuss adaptation will wrap the 3-day with an estimated $17.9M, pushing its new domestic cume to nearly $118M.

MGM/Weinstein’s Superhero Movie, which used a clever viral Tom Cruise spoof to spread the word, debuted to a so-so $3.3M. That’s less than half the opening day business of last year’s Epic Movie ($6.8M) and January’s Meet the Spartans ($6.8M), so it appears that this genre’s appeal is waning. Still, Superhero Movie should have $8.75M banked by Sunday night.