Fzsixteen

Fzsixteen is equal to \(16^{16}\) = \(16\uparrow\uparrow2\) = \(2^{64}\) = 18,446,744,073,709,551,616

Etymology
Fzsixteen is made out of the Fz- prefix and thirteen, which ends up becoming \(16^{16}\) when concatenated backwards, ergo, 16 to the power of itself.