Aditya , Although it is difficult to predict the exact ranks currently as the April  Jee Mains session has yet to take place and the actual ranks could be known only after that. However, you can predict your expected rank by this formula:-

(100 - your total score) X 869010 /100.

Also, If the number of candidates for April exam get increased to 1200000 then your final rank shall be (100 - your total score) X 1200000/100

In your case the expected rank comes out to be around 18596 .Note that this is the General or All India rank and not the category rank which is very difficult to predict at this point of time.

Now, with regards to your admission chances at MNNIT ALLAHABAD, you have a good enough chance to get some branches such as Production and Industrial Engineering, Biotechnology Engineering and also small chances to get Civil Engineering based on your category considerations, However, getting the top branches such as CSE, Mechanical Engineering, Electrical Engineering etc. would be very tough even if you belong to home state and your category is OBC. Also, you can check the previous years cutoff for MNNIT ALLAHABAD by visiting this link

https://engineering.careers360.com/articles/jee-main-cutoff-for-mnnit-allahabad

However, you have a very good percentile and you would get many state level colleges and so you should also opt for state-level counselling.

Also, you have another attempt in the April session and I would advise you to concentrate on that to increase your chances of getting the desired college.

If you want to predict what best colleges you would get based on these scores, you can use this college predictor