Hello,
As you have mentioned that your jee main cutoff rank is 2649 which indeed is a great rank to fetch any government seat in IITs or NITs. And you have a positive side that you fall under ST Category.
According to your mentioned rank you have high chances of getting CSE or ECE at NIT Meghalaya, NIT Arunachal Pradesh, NIT Delhi , NIT Goa, NIT Warangal, NIT kochi, NIT Karnataka, NIT jaipur and other core branches at the old NITs and many more NITs.

You can use the college predictor tool available on our website to predict which colleges you can get :

https://engineering.careers360.com/jee-main-college-predictor

I hope this would help you. For further queries please feel free to write me down in the comment box.