Please help me identify my new old watch

Halo. I have just bought this watch.
Anyone have ideas on how to determine model name, year, etc.?
Any guidance would be appreciated. Thank you.
Number movement: 1702050
Number case back: 12139
Cal: 421 ???

Congratulations

your watch is indeed a Cal 421 and according to the movement number 1702050
was made in 1963.
The case back **12139 is missing some digits, so I'm going to assume that the
first 2 are the same as movement ie 1712139.

The Date Your IWC app now gives a result that your case was made in 1964 and
probably delivered up to 1966.

What an interesting watch. It's seen a bit of polishing, but very nice.

Thanks Mr. MARK FLEMINGER for your information.
I search GG but found nothing about cal.421. Is it rare or just not good so
they don't produce much?
Have a nice day all. :D

Hmmm

Indeed Catherine... Indeed...

Hi Catherine and Mr Matt S, any thought? Please say to me., I'm willing to
learn.

Where did you buy it from?

@Mr Matt s. I buy from a friend and he told me he gets from eBay guy - Russia
or Ukraine.