Hello Aspirant,

According to the category rank mentioned by you in the question you have very low or almost no chances of getting into any of the IITs with any of the preparatory courses because the closing ST preparatory rank for IITs were around 500-700 and you are very far from the figure so you can hardly get any IIT.

But don't get disappointed because if you have good rank in JEE-Main then you can get good NITs also and you can predict the colleges which you can get from JEE-Main by using JEE-Main College Predictor :-

https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Even though you have very low chances but still to have a list of all those colleges which you can get based upon your JEE-Advance 2021 score you can use JEE-Advance College Predictor:-

https://engineering.careers360.com/jee-advanced-college-predictor?icn=QnA&ici=qna_answer

Note that the above prediction is made on the basis of previous year's cut-off and the cut-offs are bound to change every year depending upon various factors such as the number of candidates appearing in an examination, the number of candidates qualifying an examination, difficulty level of the paper, and so on.

You can check out previous year's cut-offs from the link given below :-

https://josaa.nic.in/Result/Result/currentorcr.aspx

JEE-Advance 2021 cut-offs are mentioned below :-

>>> Common rank list (CRL) - 10.0 (Minimum percentage of marks in each subject) - 35.0 (Minimum percentage of aggregate marks)

>>> GEN-EWS rank list - 9.0 - 31.5

>>> OBC-NCL rank list - 9.0 - 31.5

>>> SC rank list - 5.0 - 17.5

>>> ST rank list - 5.0 - 17.5

>>> CRL-PwD rank list - 5.0 - 17.5

>>> GEN-EWS-PwD rank list - 5.0 - 17.5

>>> OBC-NCL-PwD rank list - 5.0 - 17.5

>>> SC-PwD rank list - 5.0 - 17.5

>>> ST-PwD rank list - 5.0 - 17.5

>>> Preparatory course rank lists - 2.5 - 8.75

I hope this information helps you.

Good Luck!!