99 (number)

← 98 99 100 →
← 90 91 92 93 94 95 96 97 98 99 → List of numbers; Integers; ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	ninety-nine
Ordinal	99th; (ninety-ninth)
Factorization	32 × 11
Divisors	1, 3, 9, 11, 33, 99
Greek numeral	ϞΘ´
Roman numeral	XCIX, xcix
Binary	11000112
Ternary	102003
Senary	2436
Octal	1438
Duodecimal	8312
Hexadecimal	6316
Chinese/Japanese; /Korean numeral	九十九

99 (ninety-nine) is the natural number following 98 and preceding 100.

In mathematics

99 is:

a composite number
a square-prime of the form (p², q)
- the 11th composite number of this form and the third of the form (3², q)
has an aliquot sum of 57, within an aliquot sequence of two composite numbers (99,57,23,1,0), to the Prime in the 23-aliquot tree.
a Kaprekar number^[1]
a lucky number
a palindromic number in base ten
the ninth repdigit
the sum of the cubes of three consecutive integers: 99 = 2³ + 3³ + 4³.
the sum of the sums of the divisors of the first 11 positive integers.^[2]
${\frac {99}{70}}=1.4142{\color {red}8571}\ldots$ is a commonly used approximation of the irrational number √2
".99" is frequently used as a price ender in pricing.

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