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). It is the 11th composite number of this form and the third of the form (3², q). It 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]

In other fields

• ".99" is frequently used as a price ender in pricing.
• 99, the jersey number of Wayne Gretzky, since permanently retired in his honor.

References

1. "Sloane's A006886 : Kaprekar numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.
2. Sloane, N. J. A. (ed.). "SequenceA024916(sum_{k=1..n} sigma(k) where sigma(n) = sum of divisors of n)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.

External links

Media related to 99 (number) at Wikimedia Commons