Number

99

99 is a composite number, odd, a calendar year.

Arithmetic Number Deficient Number Evil Number Flippable Kaprekar Number Palindrome Recamán's Sequence Repdigit Year

Historical context — 99 AD

Calendar year

AD 99 (XCIX) was a common year starting on Tuesday of the Julian calendar.

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Historical context — 99 BC

Calendar year

Year 99 BC was a year of the pre-Julian Roman calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →

Year facts

Year type: Common year
Standard 365-day year; not divisible by 4 (or divisible by 100 but not 400).
Days in year: 365
ISO weeks: 53
Long year: contains 53 ISO weeks.
Started on: Thursday
January 1, 99
Ended on: Thursday
December 31, 99
Friday the 13ths: 3
3 Friday the 13ths this year.
Decade: 90s
90–99
Century: 1st century
1–100
Millennium: 1st millennium
1–1000
Years ago: 1,927
1927 years before 2026.

In other calendars

Hebrew: 3859 / 3860 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Earth zodiac:Pig
Sexagenary cycle position 36 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 642 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 91 / 92 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 21 / 20 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 2
Digit sum: 18
Digit product: 81
Digital root: 9
Palindrome: Yes
Bit width: 7 bits
Flips to (rotate 180°): 66
Recamán's sequence: a(389) = 99
Square (n²): 9,801
Cube (n³): 970,299
Divisor count: 6
σ(n) — sum of divisors: 156
φ(n) — Euler's totient: 60
Sum of prime factors: 17

Primality

Prime factorization: 3 ² × 11

Nearest primes: 97 (−2) · 101 (+2)

Divisors & multiples

All divisors (6)

1 · 3 · 9 · 11 · 33 · 99

Aliquot sum (sum of proper divisors): 57

Factor pairs (a × b = 99)

1 × 99

3 × 33

9 × 11

First multiples

99 · 198 (double) · 297 · 396 · 495 · 594 · 693 · 792 · 891 · 990

Sums & aliquot sequence

As consecutive integers: 49 + 50 32 + 33 + 34 14 + 15 + 16 + 17 + 18 + 19 7 + 8 + … + 15

Aliquot sequence: 99 → 57 → 23 → 1 → 0 — terminates at zero

Representations

In words: ninety-nine
Ordinal: 99th
Roman numeral: XCIX
Binary: 1100011
Octal: 143
Hexadecimal: 0x63
Base64: Yw==
One's complement: 156 (8-bit)

In other bases

ternary (3) 10200

quaternary (4) 1203

quinary (5) 344

senary (6) 243

septenary (7) 201

nonary (9) 120

undecimal (11) 90

duodecimal (12) 83

tridecimal (13) 78

tetradecimal (14) 71

pentadecimal (15) 69

Historical numeral systems

Babylonian (base 60): 𒁹 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ϟθʹ
Mayan (base 20): 𝋤·𝋳
Chinese: 九十九
Chinese (financial): 玖拾玖

In other modern scripts

Eastern Arabic ٩٩ Devanagari ९९ Bengali ৯৯ Tamil ௯௯ Thai ๙๙ Tibetan ༩༩ Khmer ៩៩ Lao ໙໙ Burmese ၉၉

Digit at this position in famous constants

π — Pi (π): Digit 99 = 6
e — Euler's number (e): Digit 99 = 2
φ — Golden ratio (φ): Digit 99 = 3
√2 — Pythagoras's (√2): Digit 99 = 7
ln 2 — Natural log of 2: Digit 99 = 8
γ — Euler-Mascheroni (γ): Digit 99 = 4

Also seen as

ASCII character

As an ASCII codepoint, 99 is c. Printable ASCII character c.

Hex color

#000063

RGB(0, 0, 99)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.99.

Address: 0.0.0.99
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.99

Unspecified address (0.0.0.0/8) — "this network" placeholder.

US numbered highway

Matches numbered highway designation:

I-99 — Bedford to Painted Post, PA/NY.

Interstate 99 on Wikipedia ↗