As of December 2023, the Riemann hypothesis has not been solved. The P vs NP that Charlie worked on, mentioned by Burdick, is also one of the Millennium Prize Problems and has not been solved either. In fact the only Millennium Problem solved to date is the Poincaré conjecture, solved 2010.
Ironically, given the theme of the episode and Ethan Burdick's research, none of the opening numbers (203,900; 90%; 56%; 48 hours) are prime numbers. The episode number (5), however, is.