i might not promise that you'd get a good college for BE/BTech with this rank and if you do what branch you'd get as there is even a huge rush in the field. but with 21K rank, you might get a good college in BArch/BPlanning.

look for colleges from this link as per your category and branch choice

https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning

all the best