The basic unit of time is the second. For smaller amounts of time they use metric prefixes.
I sometimes think of what it would like to use metric prefixes for larger units, like kiloseconds.
After 86.4 kiloseconds you run into the day, a natural period of time that doesn't fit into this metric stuff. Reality gets in the way.
How about forgetting about seconds, and use days. Then you have the milliday, (which is still longer than a minute). A microday would be the period of time we used to call 86.6ms (milliseconds).
BTW, in our system the average year is 365.2425 days long. Unexpectedly, that IS a whole number of seconds. There are 31,556,736 seconds in the average year. That's about 31.5 megaseconds per year.
1 gigasecond is approx. 31.69 years. 1 terasecond is approx. 31.69 millennia.