11,329
pages

Ninety-nines is equal to $$9 \lfloor 10^{90} / 9\rfloor = 10^{90} - 1$$, or 90 copies of 9:[1]

999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999,999
or metamathematically with interior superscription as $$9^{88}9$$

It is exactly googol/dialogue - 1.

Its prime factorization is 34 × 7 × 11 × 13 × 19 × 31 × 37 × 41 × 211 × 241 × 271 × 2,161 × 9,091 × 29,611 × 52,579 × 238,681 × 333,667 × 2,906,161 × 3,762,091 × 8,985,695,684,401 × 4,185,502,830,133,110,721.

Approximations

Notation Lower bound Upper bound
Scientific notation $$9.999\times10^{89}$$ $$1\times10^{90}$$
Arrow notation $$111\uparrow44$$ $$10\uparrow90$$
Steinhaus-Moser Notation 52[3] 53[3]
Copy notation 9[90]
Taro's multivariable Ackermann function A(3,295) A(3,296)
Pound-Star Notation #*(2,12,2,8,4,3)*10 #*(1,3,7,7,2,2,10)*7
BEAF {111,44} {10,90}
Hyper-E notation 9E89 E90
Bashicu matrix system (0)(0)(0)(0)(0)[649] (0)(0)(0)(0)(0)[650]
Hyperfactorial array notation 64! 65!
Fast-growing hierarchy $$f_2(290)$$ $$f_2(291)$$
Hardy hierarchy $$H_{\omega^2}(290)$$ $$H_{\omega^2}(291)$$
Slow-growing hierarchy $$g_{\omega^{\omega^2+\omega+4}2}(9)$$ $$g_{\omega^{\omega9}}(10)$$

Sources

1. Halm, Michael Joseph. neologisms. Archived from the original on 2014-02-19. Retrieved 2018-02-26.