According to NIST It's slightly more arbitrary than that:
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
Not sure of the numerological significance of 9192631770.
> Not sure of the numerological significance of 9192631770.
It has none. It just happens to make the new cesium-based definition of a second roughly equal to the historical definition of a second as 1/86400 of a mean solar day.
The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
Not sure of the numerological significance of 9192631770.