Fzseventy

Fzseventy is equal to \(70^{70}\) = \(70\uparrow\uparrow2\) ≈ \(1.43504\times10^{129}\).

Full decimal expansion:

1435036016098684342856030763566710717400773837392460666392490000000000000000000000000000000000000000000000000000000000000000000000

Etymology
Fzseventy is made out of the Fz- prefix and seventy, which ends up becoming \(70^{70}\) when concatenated backwards, or 70 to the power of itself.