This weekend's other new wide release — Paramount's horror story "The Ruins," about tourists who discover an ancient evil during a jungle trip — debuted at No. 5 with $7.8 million.
In narrower release, Martin Scorsese's Rolling Stones concert film "Shine a Light," distributed by Paramount Vantage, did fair business with $1.5 million.
Wong Kar Wai's romantic drama "My Blueberry Nights," starring singer Norah Jones and Jude Law, Rachel Weisz, Natalie Portman and David Strathairn, took in a solid $73,742 opening in six theaters.
Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC.
1. "21," $15.1 million.
2. "Leatherheads," $13.5 million.
3. "Nim's Island," $13.3 million.
4. "Dr. Seuss' Horton Hears a Who!", $9.1 million.
5. "The Ruins," $7.8 million.
6. "Superhero Movie," $5.4 million.
7. "Tyler Perry's Meet the Browns," $3.51 million.
8. "Drillbit Taylor," $3.5 million.
9. "Shutter," $2.9 million.
10. "10,000 B.C.", $2.8 million.