It is basically the Naval Hind... there were two models AFAIK, and they will be the standard troop helicopters for the new helicopter landing ships.
The Mistrals were supposed to carry a mix of these and the Ka-52K attack helos.
One model had a side mounted 30mm cannon next to the weapon pylon, while the other model which is the most common has a four barrel rifle calibre gatling gun behind a panel in the nose.... actually they were probably not different versions but different armament options for the same type.
I seem to recall that the model with the 30mm gun has the ammo inside the main cabin so when using it there is less room for troops inside, so they went for the other model to maximise the number of troops carried.
Would take 16 troop capacity with a grain of salt... with full gear probably less than this would be carried... maybe 8-10?
You can see the 2A42 barrel along the side of the aircraft in the above image.
Have no idea how many they have in service, but seem to remember for the anti piracy operations they used them to deliver naval infantry onto enemy ships and that sort of thing...
Will be the troop transport helo for the Ivan Gren vessels and the new helicopter carriers they will be laying down soon and could be carried by the Kuznetsov to deploy naval infantry.