Call me crazy but...

[TheLopez]

No, I don't think that's true, there are some hidden build numbers. The full release number is 1.6.1.1841 (45604). I suspect that the 1841 is the actual build number.

 

[Grey Fox]

No, I don't think that's true, there are some hidden build numbers. The full release number is 1.6.1.1841 (45604). I suspect that the 1841 is the actual build number.

Then it maybe is the amount of times it goes back from testing to bugfixing. (and the 1841 is the number of builds)

Like 1.53 goes to testing, they say still buggy, goes back to firaxis, they fix the bugs and sends version 1.54 to testing. Still buggy.... .... they send version 1.61 to testing, they say this is ready for release. Release.