Sir/Ma'am the rank for percentile 99.5257 will be around 4147(+-). This is just an estimation the actual ranks may vary after JEE Main is again conducted in April depending upon number of students appearing for it. 

And if two students have secured same percentile then the rank will be given higher to that student whose marks in Mathematics are more than the other. Also the exact qualifying marks of JEE Main is not yet announced by National Testing Agency so the cutoffs for IIITs (Indian Institute of Information Technology) cannot be predicted as of now. 

Sir/Ma'am if you have any other queries do mention it down in the comment section.