My 65 Year old English Teacher Gave me His Personal Phone Number. What do I do?

For a bit of context, I'm in 12th grade and I just turned 18. I'm a female.

My male English teacher has always been more active towards me in lessons. He constantly looks at me, gives me compliments that could just teeter on slightly weird, eg 'You always dress so nicely', and has been known for saying odd things to females before.

I just turned 18 September 3rd. As soon as I turned 18, he miraculously pressured me to move my seat to the closest to his desk under the excuse of helping another student that he doesn't even make sit next to me. Today in class, we were talking about something relating to English and, after I had gotten back to my work, he slips me a sticky note, which I still have, with his phone number on it. I was so surprised that I didn't realize what it was at first. He claimed it was so he could get to know me better. I had mentioned my dad a little bit earlier and immediately said, "Oh, get to know my dad better?"

After a rather long pause he nodded rather unconvincingly. It came to me after class that he already has contact with my parents through phone numbers given at the beginning of the year. If you truly wanted to talk to my dad about similarities and their interests, he had the means to do so without giving their daughter his phone number. This is also is first year at my highschool and all I know about his past is that he used to be in politics and law. I'm extremely uncomfortable and really don't know what to do from here.