eighteen

There are

1. five organs of knowledge, and 
2. five of actions; 
3. with muscular power, mind, understanding, and Chitta, and 
4. with also the three attributes of Sattwa, Rajas, and Tamas, the tale, it has been said, comes up to seventeen. 
5. The eighteenth in the enumeration is he who owneth the body, 

Indeed, he who lives in this body is eternal. All those seventeen (with Avidya or Ignorance making eighteen), dwelling in the body, exist attached to him who owns the body. When the owner disappears from the body, those eighteen (counting Avidya) cease to dwell together in the body.

http://www.sacred-texts.com/hin/m12/m12b102.htm