I was just made aware that today is the 20,000 day since January 1, 1970. If you don't feel like downloading, building and running ud, the “UNIX day calculator”, you can check the current UNIX day (with some approximation) using standard command-line tools:

$ echo $(( $(date +%s) / 86400 ))
20000

Explanation: date is a tool that prints the current date. You can choose the format in which the date is printed using the command-line +format syntax, and %s is the format specifier “number of seconds since the epoch”, aka Unix Time where the epoch on UNIX systems is January 1, 1970 at midnight UTC. If we take its value and divide it by 86,400, which is the number of seconds in a day, we get the number of days since the epoch. (The $(( ... )) syntax is used to make simple mathematical operations with integer values directly on the command line.)

Fun fact, the same tools can be used in reverse to determine the date of any particular Unix day. For example, if I want to know which was the 10,000th day in Unix time, I would do something like

$ date -u -d@$((86400*10000)) +%Y-%m-%d
1997-05-19

Here we're passing date the parameter -u to tell it to use UTC, and -d to tell it to give us the date at the given time, rather than now. And we want this time to be specified as Unix Timer (which is specified by the @), with 86400×10000 meaning “10,000 days since the epoch” (again, 86,400 being the number of seconds in a day). The +%Y-%m-%d specification tells date to output the given date in year-month-day format.

Now, as I've mentioned before, if you're nerding out on dates there's not much of a point on getting excited on numbers that are only interesting in base 10. Especially when the next such interesting number would be on February 20, 2052, neary 28 years from now.

On the other hand, we're even worse off with power-of-two numbers, since 214 days was on November 10, 2014, while 215 days will be on September 19, 2059.

Damnit.