For the JEE main January exam 869010 students appeared for the exam therefore you can calculate the rank by the following formula

(100-percentile)*8690.10

So you are calculated rank is 30415.

Since this is not the final rank if the number of a student appearing for JEE main April session get higher than your rain will go at lower also it will change your because the best of the to score will be considered for the rank calculation so direct formula for percentile to rank using the number of candidates appeared cannot be used but this is rough figure as of now you are standing at nearly this rank .

To calculate the JEE main rank,you can use this formula ((100-your total percentile)*869010/100).This formula will give your general category rank(Common list rank).And your rank is approximately 30,415.It will be difficult to predict your OBC rank because we dont have the exact data of number of  OBC candidates who have appeared for the exam.To know about all the possibilities of your admission into various colleges,visit the below given website.You will have to enter the details asked such as your percentile,category,home state etc..and the possibilities will be predicted.