Exillion

The exillion is equal to \(10^{3 \cdot 10^{3 \cdot 10^{18}}+3}\), or \(10^{3 \cdot 10^{3 \cdot \text{quintillion}} + 3}\). The term was coined by Jonathan Bowers.

Etymology
The name of this number is based on the suffix "-illion" and SI prefix "exa-".