You should get 88 keys ideally. Here's a few inexpensive ones in order of preference:
Again, digital piano. I would recommend the Yamaha P45. I've been using it for roughly 2 years now and it's basically perfect for piano playing. It's got most of what you want to look out for: midi functionality, weighted keys, etc.
I just recently got a Yamaha P-45 with the furniture stand for $400 from costco and it’s been great, super basic as far as features go, like 12 instruments and midi support, but all I was looking for was a simple digital piano with weighted keys and a pedal to play on at home and not bother neighbors. It’s on amazon for 450 without a stand, or like 580 with the furniture stand etc. - Yamaha P45 88-Key Weighted Action Digital https://www.amazon.com/dp/B00UJ9LNDK/ref=cm_sw_r_cp_api_i_H9htCb60ZY3XS