That's roughly equivalent to what I noticed long ago, that the number of seconds in a year is almost exactly equal to 10^7.5. It's convenient to memorize the common logs of common things, so I can do mental arithmetic on very large and very small quantities when I'm out walking, which is when I do my best thinking. Other weird units include the microfortnight, used in the VMS operating system, the hubble-barn unit of volume (which combines a very small area with a very long distance), and the Planck units, which define the speed of light, the gravitational constant, and Planck's constant as being 1, and derive all other units from those. In the Planck system the units of mass and energy are of reasonable size, but pretty much all other units are either absurdly large or ridiculously small. Also see https://en.wikipedia.org/wiki/List_of_humorous_units_of_measurement