Megafugasix

Megafugasix is equal to 6↑↑6, or 6 tetrated to 6. It is approximately equal to $10^{10^{10^{10^{36,305}}}}$ or $E36,305\#4$ in Hyper-E notation.

Googology Wiki user Hyp cos calls this number hexabo, and it's equal to s(6,6,2) in strong array notation.^[1]

This number is also equal to s(6,2,3), s(6,2,1,2), s(6,2{2}2), and 3$ (the superfactorial of 3).

Etymology

The name "megafugasix" is formed by adding the megafuga- prefix to 6.

The name "hexabo" is based on the word "hexa" (Greek for six), meaning a base-6 number.

Notation	Approximation
Arrow notation	$6 \uparrow\uparrow 6, 6 \uparrow\uparrow\uparrow 2$ (both exact)
Bowers' Exploding Array Function	$\{6,6,2\}, \{6,2,3\}$ (both exact)
Bird's array notation	$\{6,6,2\}, \{6,2,3\}$ (both exact)
Chained arrow notation	$6\rightarrow6\rightarrow2, 6\rightarrow2\rightarrow3$ (both exact)
Hyper-E notation	$E(6)1\#6$ (exact)
Hyperfactorial array notation	$(((10,160!)!)!)!$
Scientific notation	$10^{10^{10^{2.0692\times10^{36,305}}}}$
Fast-growing hierarchy	$f_2(f_2(f_2(f_2(f_2(13)))))$
Hardy hierarchy	$H_{\omega^25}(13)$
Slow-growing hierarchy	$g_{\varepsilon_0}(6)$ (exact)

Notation	Approximation
Arrow notation	\(6 \uparrow\uparrow 6, 6 \uparrow\uparrow\uparrow 2\) (both exact)
Bowers' Exploding Array Function	\(\{6,6,2\}, \{6,2,3\}\) (both exact)
Bird's array notation	\(\{6,6,2\}, \{6,2,3\}\) (both exact)
Chained arrow notation	\(6\rightarrow6\rightarrow2, 6\rightarrow2\rightarrow3\) (both exact)
Hyper-E notation	\(E(6)1\#6\) (exact)
Hyperfactorial array notation	\((((10,160!)!)!)!\)
Scientific notation	\(10^{10^{10^{2.0692\times10^{36,305}}}}\)
Fast-growing hierarchy	\(f_2(f_2(f_2(f_2(f_2(13)))))\)
Hardy hierarchy	\(H_{\omega^25}(13)\)
Slow-growing hierarchy	\(g_{\varepsilon_0}(6)\) (exact)