Here is a bit of History trivia. Advertised as the “Precision Miniature Camera,” the Nikon I went to market in 1948. The prototype was ready in 1947 and was stamped with Serial No. 6091. Only 20 prototypes were run and No. 6091 is known as the very first Nikon camera (Model No. 1).
The Nikon I was a 35mm film camera that accepted interchangeable lenses. An early brochure for the camera listed 4 Standard lenses (all 50mm; F3.5, F2, F1.8 and F1.5), 1 wide-angle lens (35mm F3.5) and 2 telephoto lenses (85mm F2 and 135mm F4). Shutter speed ranged from T, B, 1 sec. to 1/500 sec.
No. 6091 was the first Nikon I model, which is known today as the first Nikon camera. The number signifies that it was the first model in a run of only 20 prototypes (Nos. 6091-60920), which were manufactured in 1947.
According to notes that were found with the camera, the design division had entrusted Model No. 1 to the engineering division archives, where it had been carefully stored ever since. However, it seems that the number of people who knew of its existence had dwindled in the wake of the demise of the engineering division brought about by organizational changes, and at some point it had been forgotten about. Then, exactly 50 years after its creation, the missing Model No. 1 saw the light of day again.
Read more about the Nikon I at: Nikon History.