This particular case it's not an easy one to solve and I do believe that a lot of information was lost during all these years, maybe some private documents may help in a near future.

Well as we may see the roundels (cocardes) are french style as the serial number on the rudder. But as far as I know the french aircraft displayed individual numbers over the fuselage in different colors sometimes side by side the escadrille insignia. I guess only the british used a combination code of a letter and a number. But the RFC aircraft also displayed their roundel type colours and a large serial number on the rudder not seen here.
After a closer look of a digitalized 650 dpi pic, I guess the serial number is N 1627 and not 3627. The internet Nieuport page of serial numbers doesn't help in this particular case.
Let's wait and see...
Best Regards