Sesquillion is a large noninteger defined by SuperJedi224 as equaling 103*1.5+3 = 107.5 ≈ 31622776.60168[1]. The name is derived from the prefix "sesqui-", meaning one and a half, and the suffix "-illion" as defined in the short scale. It is equal to the square root of one quadrillion.

The same name has also been suggested by John Savard as an alternative name for billion[2], which is equal to 106*1.5. It would be the 1.5th -illion in the long scale.

The term is also an obscure alternative to "zillion" to refer to an indefinite large number.

Approximations Edit

Notation Lower bound Upper bound
Scientific notation \(3.162\times10^7\) \(3.163\times10^7\)
Arrow notation \(74\uparrow4\) \(75\uparrow4\)
Steinhaus-Moser Notation 8[3] 9[3]
Copy notation 2[8] 3[8]
Taro's multivariable Ackermann function A(3,21) A(3,22)
Pound-Star Notation #*(53)*4 #*(23)*5
BEAF {74,4} {75,4}
Hyper-E notation 3E7 4E7
Hyperfactorial array notation 10! 11!
Fast-growing hierarchy \(f_2(20)\) \(f_2(21)\)
Hardy hierarchy \(H_{\omega^2}(20)\) \(H_{\omega^2}(21)\)
Slow-growing hierarchy \(g_{\omega^7\times3}(10)\) \(g_{\omega^7\times2}(11)\)


  1. Almost Infinite