How do you compare in size to the smallest and largest things in of universe?

Vsauce makes an interesting claim at the end of this video. Can anyone verify?

So, the smallest thing in the universe is a plank length.

And the largest thing of the universe, is well… The Universe.

As Vsauce claims, the number of plank lengths it would take to stretch across one human brain cell, is the same number of brain cells it would take to stretch across the entire universe.

Is there any real relationship there, enough to claim that human beings are sized precisely in the middle of all known physical phenomenon? Anyone here to check the math on that?