The NCAA actually doesn't recognize a football championship.
Here's another site saying they have 10.
http://www.cfbdatawarehouse.com/data...nal_champs.php
(probably a little more accurate than wikipedia).
There are some "claimed NC's", such as the one in 1980 when Montgomery Full Season Championship proclaimed them national champions.
I'm not sure about the "12" number though, except from Wikipedia.
By some standards, Oklahoma also has 23 NC's
http://www.cfbdatawarehouse.com/data...nal_champs.php
Anyhow, in the modern era, they have 6 -- largely owed to a Sigma Nu named Paul Bryant