Marioplex

Marioplex (10^12431) is a large number named by youtube user MatPat, in this video.

History
MatPat invented this number in n August 6, 2017, when trying to calculate the number of possible levels in the game Super Mario Maker.

This number was calculated by repeated use of the fundamental principle of counting, and represents, very roughly, the fraction of the number of possible levels in the aforementioned game that are both fun and completable.

As the exact number of levels with said properties is impossible to calculate, a Fermi estimate was used to define the number.

Properties
As it is larger than the Googol to the 100th power, Marioplex is impossible to be written in the observable universe.

In fact, even if each digit were not made of particles, and occupied the smallest possible amount of volume that is thought to exist (the Planck Volume), many googols of copies of the universe would be needed to express even a small fraction of a Marioplex.