2 to the 31 — many systems keep track of time as seconds since January 1, 1970 (“Epoch time”), and older systems use a signed 32-bit integer. Modern 64-bit systems don’t have a Y2038 problem. It’s all the 32-bit systems that we have to worry about (embedded systems and old computers), but they’ll probably mostly get cycled out in the next 16 years. ¯\_(ツ)_/¯As a computer journalist, I asked some experts about this, and they claim that they've got some ways to get around that limit. Maybe 2038 won't be that bad, after all.