Your NEET rank depends on the score, Category, no.of Candidates who appeared for the exam, No.of Candidates who scored the same rank and tie breaking criteria. If you have had a look at 2019 merit list, though the 2nd and 3rd rank candidates scored the same rank, the ranks were given as 2nd and 3rd depending on few criteria, But in general, if your NEET score is 550, you rank might be around 25000.