Hi aspirant
Congratulations for scoring so well. With a score of 646 you do have chances of fetching a seat in AIIMS, Bibi nagar, Hyderabad. However the odds are 50:50.
According to the past trends, the All India rank at 646 marks was around AIR 5k-5.2k.

You can however predict your rank for NEET 2022 using our rank predictor. Use the link provided here:
https://medicine.careers360.com/neet-rank-predictor?utm_source=qna&utm_medium=neet_rp
You can also predict what college you might get using the predicted rank. Check the link below.
https://medicine.careers360.com/neet-college-predictor?utm_source=qna&utm_medium=neet_cp
Now let's have a look on the closing ranks of the colleges you wish to get a seat allotted in.
Since you have not mentioned what category you belong, I am going to list the closing ranks for each category individually.
AIIMS, Bibi nagar, Hyderabad
UR  - 4042
OBC- 6841

Gandhi medical College, Secunderabad
UR - 4014
OBC - 5941
EWS- 5728
SC- 42201

For more precise information, I am gonna need your category. With the information you can see that you might get a seat In Gandhi medical College. However the stakes might change according to the cut off this year.
Hope this answers your query
All the best:)

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