Your rank can be predicted by using the formula, (100-your total percentile)*869010/100. In your case, your approximate rank would be 278083. Let's say the number of candidates for April exam increased to 12,00,000 then your final rank shall be (100 - your total score) X 12,00,000/100.

In 2019, the cut offs for various streams for NIT Agartala for Home State Candidates has been as follows:

Biotechnology and Biochemical: 19773

Chemical: 18167

Civil: 17585

CSE: 9562

Electrical: 17440

ECE: 14067

Mechanical: 16630

Electronics: 19636

Production: 20048

Now cut offs change every year depending on various factors but the ranks cannot go as higher as your rank is. So if you want a seat in NIT Agartala, you should appear for April session.