The famous Korean thriller involving a mathematician and a "perfect" murder is titled "Perfect Number" (Korean title: Yong-suja-yeon), but it was released in 2012. There is no major movie simply titled "Perfect Number" released in 2012 and 2014. You likely found the correct movie (the 2012 Korean film), but encountered conflicting dates on different streaming sites.
The Perfect Number (2012) - A Detailed Review
Digital Purchase/Rent: Available on Apple TV, Google Play, and TrueID. perfect number 2012 english subtitles full
If you're looking for English subtitles, I can suggest some resources:
00:35:31,800 --> 00:35:35,100 That is the variable we haven't solved for. The famous Korean thriller involving a mathematician and
00:35:23,600 --> 00:35:26,900 The autopsy says he died at 10 PM. She was at the convenience store at 10 PM.
00:18:33,600 --> 00:18:36,900 I just wanted to see where it happened. The Perfect Number (2012) - A Detailed Review
Critics generally praise the film for its strong performances and visual style, though some note it leans heavily into sentimentality compared to other adaptations: