Hi Siddharth, hope you are doing well, with your rank of 21835 you can expect iiits for sure. But for NIT's you need to get still more good rank. There are chances that you can get into NIT's as well but you may not get for your desired streams like cse,ece but you can get into other streams like mechanical and civil. I suggest you apply for counselling in all NIT's and patiently get the seat in the NIT. To know more about the admissions in jee mains kindly go through the rank predictor in careers. The link for the rank predictor in jee mains is given below, kindly go through it

https://engineering.careers360.com/jee-main-college-predictor?utm_source=C360&utm_medium=qna&utm_campaign=jee-main-college-predictor

I think it is helpful!!!

Keep smiling:)

Wish you good luck!:)