Zettillion

The zettillion is equal to \(10^{3 \cdot 10^{3 \cdot 10^{21}}+3}\), or \(10^{3 \cdot 10^{3 \cdot \text{sextillion}} + 3}\). The term was coined by Jonathan Bowers.

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