I have the almost identical model Ikonta 521 but I believe mine to be post war; serial number P61065, 1949/1950. Single coated Novar 7.5cm/f4.5 lens in a Compur shutter. In the case of this camera, the model number and serial number are impressed on the leatherette of the back.
It's a cracking camera, beautifully made with a more than adequate lens. Of course it would be nice if I had a version with the Tessar!
I have two other Ikontas; a 1937 521/2 (6x9) with a Tessar lens in Compur shutter, a prized possession because it's in perfect working order, and a 1936 520/16 (6x6) with a Novar lens in an unnamed shutter. In both cases the model and serial numbers are stamped on the back.