What personality type is this guy?

I'm just wondering what type this guy in my class that I speak to sometimes is. I have a feeling he could be a INTJ. I know hes definitely a introverted type. I'm an INTP hes a bit similar to me.

-Hes quite intelligent good at most subjects
-He really loves maths solving problems and its his favourite subject , he also likes english
-Hes a quiet , and reserved he only talks to people he knows well
-Hes nice and polite
-He doesn't use big hand gestures ,
-I think he prefers one-on-one conversations , he doesn't really talk much in a group
- Hes more of a listener than a talker
-He doesn't flirt even though there are girls
-He won't talk in class unless he knows the answer
-He has strong opinions and occasionally and would think his opinion right
-He doesn't go out much at the weekends
-He would never really volunteer to do anything
-He gets along with most people
-He doesn't like being the leader
-He observes things alot
-He seems really organized
-Hes not into art or photography
-He doesn't join any social network sites as he doesn't like them
-Hes self-confident
-Hes not that touchy feely
-He doesn't really show much expression o his face when he speaks he has a serious face but smiles sometimes
-Hes the type of guy who'd he'll answer you if you talk to him but he's not much of a conversation person