The heptacthulhum (also called hexacthularxihect) is equal to E100#^^^^^#100 = E100#{5}#100 in Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number is based on the words "heptation" and "Cthulhu".

It is pronounced like this.

Approximations in other notations

Notation Approximation
BEAF \(\{X,X,1,4\}\ \&\ 100\)
Bird's array notation \(\{100,100 [1 [1\neg3] 1 [1\neg3] 1 [1\neg3] 2] 2\}\)
Hyperfactorial array notation \(100![1(1)1(1)1(1)2]\)
Fast-growing hierarchy \(f_{\varphi(3,0,0)}(99)\)
Hardy hierarchy \(H_{\varphi(3,0,0)}(100)\)
Slow-growing hierarchy \(g_{\vartheta(\Omega_{2}3)}(100)\)


  1. Saibian, Sbiis. 4.3.4 - Forging Extended Cascading-E Numbers Part II. Retrieved June 2014.