209
209 is a composite number, odd, a calendar year.
209 (two hundred nine) is an odd 3-digit number. It is a composite number with 4 divisors, and factors as 11 × 19. Written other ways, in Roman numerals it is CCIX and in binary, 11010001.
Interestingness
Historical context — 209 AD
Calendar year
Year 209 (CCIX) was a common year starting on Sunday of the Julian calendar.
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Historical context — 209 BC
Calendar year
Year 209 BC was a year of the pre-Julian Roman calendar.
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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
-
Sunday
January 1, 209
- Ended on
-
Sunday
December 31, 209
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
200s
200–209
- Century
-
3rd century
201–300
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,817
1817 years before 2026.
In other calendars
- Hebrew
-
3969 / 3970 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Earth zodiac:Ox
Sexagenary cycle position 26 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
752 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
201 / 202 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
131 / 130 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 11 × 19
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√209 = [14; (2, 5, 3, 2, 3, 5, 2, 28)]
Period length 8 — the block in parentheses repeats forever.
Representations
- In words
- two hundred nine
- Ordinal
- 209th
- Roman numeral
- CCIX
- Binary
- 11010001
- Octal
- 321
- Hexadecimal
- 0xD1
- Base64
- 0Q==
- One's complement
- 46 (8-bit)
- Scientific notation
- 2.09 × 10²
- As a duration
- 209 s = 3 minutes, 29 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- σθʹ
- Mayan (base 20)
- 𝋪·𝋩
- Chinese
- 二百零九
- Chinese (financial)
- 貳佰零玖
Digit at this position in famous constants
- π — Pi (π)
- Digit 209 = 9
- e — Euler's number (e)
- Digit 209 = 1
- φ — Golden ratio (φ)
- Digit 209 = 7
- √2 — Pythagoras's (√2)
- Digit 209 = 9
- ln 2 — Natural log of 2
- Digit 209 = 4
- γ — Euler-Mascheroni (γ)
- Digit 209 = 2
Also seen as
UTF-8 encoding: C3 91 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.209.
- Address
- 0.0.0.209
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.209
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 209 is an active NANP area code (North American Numbering Plan).
- Primary area
- Stockton / Modesto
- 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, 209 Hz is closest to:
- Concert pitch (A4 = 440 Hz): G♯3 (207.7 Hz, +11¢)
- Scientific pitch (C4 = 256 Hz): G♯3 (203.2 Hz, +49¢ — about midway to A3)
- Baroque pitch (A4 = 415 Hz): A3 (207.5 Hz, +12¢)
Related reading
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.