Thanks for the question and congratulations for the great rank. 

With 6406 AIR, you can get following colleges -

Jawaharlal Nehru Medical College, Bhagalpur

Government Medical College, Bettiah

Vardhman Institute of Medical Sciences, Pawapuri, Nalanda

Anugrah Narayan Magadh Medical College, Gaya

Darbhanga Medical College, Lehriasarai

Sri Krishna Medical College, Muzaffarpur

All the above colleges you can get in 15%quota.

Indira Gandhi Institute of Medical Sciences, Sheikhpura, Patna  can be achieved under the state quota. 

All the best