Heptlastillion is equal to 103*1021.[1] The term was coined by Aarex Tiaokhiao.
Approximations[]
| Notation | Lower bound | Upper bound |
|---|---|---|
| Arrow notation | \(1000\uparrow10\uparrow21\) | |
| Down-arrow notation | \(1000\downarrow\downarrow8\) | |
| Steinhaus-Moser Notation | 16[3][3] | 17[3][3] |
| Copy notation | 2[2,4] | 3[3[22]] |
| H* function | H(999H(5)) | H(H(6)) |
| Taro's multivariable Ackermann function | A(3,A(3,70)) | A(3,A(3,71)) |
| Pound-Star Notation | #*((1))*(3,0,6)*3 | #*((1))*(3,3)*6 |
| BEAF | {1000,{10,21}} | |
| Hyper-E notation | E(3E21) | |
| Bashicu matrix system | (0)(1)[8] | (0)(1)[9] |
| Hyperfactorial array notation | (21!)! | (22!)! |
| Fast-growing hierarchy | \(f_2(f_2(67))\) | \(f_2(f_2(68))\) |
| Hardy hierarchy | \(H_{\omega^22}(67)\) | \(H_{\omega^22}(68)\) |
| Slow-growing hierarchy | \(g_{\omega^{\omega^{\omega2+1}3}}(10)\) | |