999 (number)

This article is about the natural number. For the emergency telephone number, see 999 (emergency telephone number). For other uses, see 999 (disambiguation).

← 998 999 1000 →
List of numbers Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	Nine hundred [and] ninety-nine
Ordinal	999th (Nine hundred [and] ninety-ninth)
Factorization	33 × 37
Divisors	1, 3, 9, 27, 37, 111, 333, 999
Greek numeral	ϠϞΘ´
Roman numeral	CMXCIX, cmxcix
Binary	11111001112
Ternary	11010003
Senary	43436
Octal	17478
Duodecimal	6B312
Hexadecimal	3E716
Base 36	RR36

999 (nine hundred [and] ninety-nine or nine-nine-nine) is a natural number following 998 and preceding 1000. The largest 3-digit decimal integer. With a thousand:

• 1999 = centered triangular number, ^[1] number of regular forms in a myriagram.

In mathematics

• 999 is a Kaprekar number as its square, 999×999 = 998001, which can be broken to 998 and 1, whose sum 999 has a square that returns to 998001. ^{[2] [3]}
• 999 is a taxicab number as it is the difference between two cubes. For example, 999 can be expressed 10³ - 1³ = 1000 - 1 and 12³ - 9³ = 1728 - 729.
• A palindromic number in bases 10, 14 (515₁₄), and 36 (RR₃₆).
  • A repdigit in bases 10 and 36.
• The largest number in English not containing the letter 'o' in its name, when using short scale.
• A base-10 Harshad number because ${\displaystyle {\frac {999}{(9+9+9)}}=37}$, a whole number.
• A nude number because it is divisible by each of its digits.

Other fields

• In some parts of the world, such as the UK and Commonwealth countries, 999 (pronounced as 9-9-9) is the main emergency telephone number, it also functions in many other countries.
• 999 was a London punk band active during the 1970s.
• 999 is also the short name for the visual novel Nine Hours, Nine Persons, Nine Doors .
• 999 is the last 3 digit number. It is also the last number in English written without a comma, as numbers above 999 must require a comma (e.g. numbers starting from 1,000 or more).
• 999 is the number the late rapper Juice WRLD chose as his moto, he explains it as ”999 is 666 (the Antichrist’s number flipped upside down) to resemble taking carnality and turning it upside down turning it into spirituality.“

References

1. Sloane, N. J. A. (ed.). "SequenceA005448(Centered triangular numbers: 3n(n-1)/2 + 1)". The On-Line Encyclopedia of Integer Sequences . OEIS Foundation.
2. "Sloane's A006886 : Kaprekar numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-02.
3. "Properties of number 999". www.numbersaplenty.com. Archived from the original on 2024-06-13. Retrieved 2025-04-03.