Andyy, 2-4?
The real question is the aircraft's ability to fly with the engines on one wing.
A 4 engined aircraft with embedded engines has to be capable of flight assuming 2 engines on one side become inoperable. Where the aircraft, for fuel economy, shuts down an engine on each side of it must be capable of flying on one engine.
In comparison with a 2 engine aircraft it is now on 25% of its installed power until another engine is restarted. Loss of one engine of two leaves 50% installed power. As for better survivability from bird strikes, the Nimrod at Kinloss and the E3 at Elmendorf disprove that.
The consider all the disadvantages of 4 engines - greater installed weight, more complex utility services including weight, increased drag, which all add to increased fuel burn together with increased fuel weight for the same endurance.
I submit that 4 engines give an unjustified confidence where modern twin-jets are technically the better option and no less safe.