66 days + 12 hours are 5,745,600,000,000,000 ns. The log2 of this is 52.351...

Javascript and some other languages only have integer precision up to 52 bits then they switch to floating point.

Curious.

Isn't 32bit counter 49 days? Assuming that one was counting milliseconds, at least.

Only remember that because that's the limit for Windows 95…