Is he interested? (I'm 20, he's 25)

Just curious...

Recently I made this friend and I usually hang around with her on campus, around a certain time we have lunch at the cafeteria. At the beginning of this semester, she introduced me to one of her friends/co-workers (they work at that popular electronics store) He used to always sit at a different table and would simply wave or chit-chat with her about work. Never really said much to me, nor did I engage in conversation with him. One day, I had a few things to do and said I would meet her at the cafeteria. I show up and he's sitting with her at a table talking, I joined them (of course) she was working on some class notes and I was eating, so was he, and we got to talking - we found out, he was 25! and this whole time she didn't even know nor did I since he looks young, anyways...she had to leave and I talked to him a little more about medicine and other mutual interests. Randomly, another day we're sitting at another table (my friend and I ) and comes and sits by me and her...we get to talking a little more, joke around and she leave us early as usual. This is the strange part: apparently one of his classes got moved he asked me if I wanted to walk around campus and find it with him, so I said sure...we stalked this chick he suspected was in his class and talked a bit along the way. When he got there he invited me to a party (not the crazy drinking type) ,a simple friends gathering at his fam's place. I wasn't going to be able to make it but he asked me for my number anyways...

p.s: our mutual friend is married.

question: we've barely talked, he's more her friend than mine, why did he invite me to his party and ask me for my number?
Is he interested? (I'm 20, he's 25)
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