911
911 is a prime, odd, a calendar year.
911 (nine hundred eleven) is an odd 3-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in Roman numerals it is CMXI and in binary, 1110001111.
Interestingness
Historical context — 911 AD
Calendar year
911 (CMXI) was a common year starting on Tuesday of the Julian calendar.
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Historical context — 911 BC
Decade
The 910s BC is a decade that lasted from 919 BC to 910 BC.
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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, 911
- Ended on
-
Thursday
December 31, 911
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Decade
-
910s
910–919
- Century
-
10th century
901–1000
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,115
1115 years before 2026.
In other calendars
- Hebrew
-
4671 / 4672 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
298 / 299 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Goat
Sexagenary cycle position 8 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1454 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
289 / 290 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
903 / 904 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
833 / 832 Saka
Indian national calendar; year starts in March.
Properties
Primality
911 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√911 = [30; (5, 2, 8, 5, 1, 11, 4, 4, 2, 1, 1, 29, 1, 1, 2, 4, 4, 11, 1, 5, 8, 2, 5, 60)]
Period length 24 — the block in parentheses repeats forever.
Representations
- In words
- nine hundred eleven
- Ordinal
- 911th
- Roman numeral
- CMXI
- Binary
- 1110001111
- Octal
- 1617
- Hexadecimal
- 0x38F
- Base64
- A48=
- One's complement
- 64,624 (16-bit)
- Scientific notation
- 9.11 × 10²
- As a duration
- 911 s = 15 minutes, 11 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹𒁹𒁹𒁹𒁹 𒌋𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓏺
- Greek (Milesian)
- ϡιαʹ
- Mayan (base 20)
- 𝋢·𝋥·𝋫
- Chinese
- 九百一十一
- Chinese (financial)
- 玖佰壹拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 911 = 4
- e — Euler's number (e)
- Digit 911 = 3
- φ — Golden ratio (φ)
- Digit 911 = 9
- √2 — Pythagoras's (√2)
- Digit 911 = 1
- ln 2 — Natural log of 2
- Digit 911 = 3
- γ — Euler-Mascheroni (γ)
- Digit 911 = 3
Also seen as
UTF-8 encoding: CE 8F (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.143.
- Address
- 0.0.3.143
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.3.143
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 911 Hz is closest to:
- Concert pitch (A4 = 440 Hz): A♯5 (932.3 Hz, -40¢)
- Scientific pitch (C4 = 256 Hz): A♯5 (912.3 Hz, -2¢)
- Baroque pitch (A4 = 415 Hz): B5 (931.6 Hz, -39¢)
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.