Firstly i would like to tell you that NMIMS's engineering college accepts the scores of NPAT exam which it conducts as per NMIMS University rules. According to the marks obtained you can get admission into the branch of engineering desired.

You can calculate your rank using
rank formula for jee mains is is (100 - your total score) X 869010 /100.100 (tel:869010100100) - your total percentile score is the percentage  of people ahead of you. 869010 (tel:869010) are the number of candidates appeared for Jan exam.If the number of candidates for April exam increased to 1200000 (tel:1200000) then your final rank shall be (100 - your total score) X 1200000/100 (tel:1200000100)
So your approximate general  rank will be 165111

You can check in wich college you can get admission using career 360 college predictor