What to do about this girl?

I am 23 and the girl is 14. The thing is that this girl is always touching me for no reason. She was sitting behind me in church and she suddenly touched the back of my neck to see if I was "ticklish". She also touched my arm a couple of times in a playful manner. Many times that she walks around me she pokes me, shoves me playfully, or punches my stomach softly in a playful manner. She also hugs me as a greeting everytime she sees me. Why does she do these things? Does she have a crush on me? If she does, how can I turn her down without hurting her feelings since she is a very nice, friendly girl? It's awkward because she does this in front of people and I don't want people to start thinking things. Give me some advice about this.