Star Wars takes place entirely within one galaxy, and the number of supernova per galaxy is something like 1 per century, so, nah, Han was just bullshitting to stall for time while his busted-ass computer cobbled together numbers.
2^64 planck times is 9.9e-25 seconds. Planck times are really tiny.
2^64 nanoseconds is 584 years.
The context was timestamps -- I (playfully) figured out how many bits we'd need to count Planck times before the expected heat death of the universe, thus being truly future proof. I was expecting the answer to be a rediculous number, but in fact it was more in the "not efficient, but definitely feasible" range.
Floating point gets us there too, of course, but it has its own drawbacks and it isn't nearly as funny.