909
909 is a composite number, odd, a calendar year.
909 (nine hundred nine) is an odd 3-digit number. It is a composite number with 6 divisors, and factors as 3² × 101. Its digits read the same forwards and backwards, so it is a palindromic number. Written other ways, in Roman numerals it is CMIX and in binary, 1110001101.
Interestingness
Historical context — 909 AD
Calendar year
Year 909 (CMIX) was a common year starting on Sunday of the Julian calendar.
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Historical context — 909 BC
Decade
The 900s BC is a decade that lasted from 909 BC to 900 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
- 52
- Started on
-
Tuesday
January 1, 909
- Ended on
-
Tuesday
December 31, 909
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
900s
900–909
- Century
-
10th century
901–1000
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,117
1117 years before 2026.
In other calendars
- Hebrew
-
4669 / 4670 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
296 / 297 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Earth zodiac:Snake
Sexagenary cycle position 6 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1452 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
287 / 288 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
901 / 902 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
831 / 830 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 2 × 101
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√909 = [30; (6, 1, 2, 6, 2, 1, 6, 60)]
Period length 8 — the block in parentheses repeats forever.
Representations
- In words
- nine hundred nine
- Ordinal
- 909th
- Roman numeral
- CMIX
- Binary
- 1110001101
- Octal
- 1615
- Hexadecimal
- 0x38D
- Base64
- A40=
- One's complement
- 64,626 (16-bit)
- Scientific notation
- 9.09 × 10²
- As a duration
- 909 s = 15 minutes, 9 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ϡθʹ
- Mayan (base 20)
- 𝋢·𝋥·𝋩
- Chinese
- 九百零九
- Chinese (financial)
- 玖佰零玖
Digit at this position in famous constants
- π — Pi (π)
- Digit 909 = 9
- e — Euler's number (e)
- Digit 909 = 2
- φ — Golden ratio (φ)
- Digit 909 = 8
- √2 — Pythagoras's (√2)
- Digit 909 = 3
- ln 2 — Natural log of 2
- Digit 909 = 6
- γ — Euler-Mascheroni (γ)
- Digit 909 = 5
Also seen as
As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.141.
- Address
- 0.0.3.141
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.3.141
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 909 is an active NANP area code (North American Numbering Plan).
- Primary area
- San Bernardino / Riverside
- Region
- California
- Country
- United States
Most NANP area codes have multiple overlays in dense regions; the primary area listed is the historic/largest population center for this code.
Heard as a frequency, 909 Hz is closest to:
- Concert pitch (A4 = 440 Hz): A♯5 (932.3 Hz, -44¢)
- Scientific pitch (C4 = 256 Hz): A♯5 (912.3 Hz, -6¢)
- Baroque pitch (A4 = 415 Hz): B5 (931.6 Hz, -43¢)
Related reading
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.