1,809
1,809 is a composite number, odd, a calendar year.
Notable events — 1809 AD
- Feb 12 Abraham Lincoln and Charles Darwin are both born.
- May 17 Napoleon annexes the Papal States; Pope Pius VII excommunicates him.
- Jul 5 Napoleon defeats the Austrians at Wagram.
- Sep 17 The Treaty of Fredrikshamn ends Sweden's war with Russia; Finland becomes a Russian grand duchy.
- Aug 9 Lord Byron leaves England, beginning the journey that inspires Childe Harold's Pilgrimage.
Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0
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, 1809
- Ended on
-
Sunday
December 31, 1809
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Easter Sunday
-
April 2
Sunday, April 2, 1809
- Decade
-
1800s
1800–1809
- Century
-
19th century
1801–1900
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
217
217 years before 2026.
In other calendars
- Hebrew
-
5569 / 5570 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1223 / 1224 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
-
2352 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1187 / 1188 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1801 / 1802 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1731 / 1730 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 18
- Digit product
- 0
- Digital root
- 9
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 9,081
- Flips to (rotate 180°)
- 6,081
- Recamán's sequence
- a(16,081) = 1,809
- Square (n²)
- 3,272,481
- Cube (n³)
- 5,919,918,129
- Divisor count
- 8
- σ(n) — sum of divisors
- 2,720
- φ(n) — Euler's totient
- 1,188
- Sum of prime factors
- 76
Primality
Prime factorization: 3 3 × 67
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand eight hundred nine
- Ordinal
- 1809th
- Roman numeral
- MDCCCIX
- Binary
- 11100010001
- Octal
- 3421
- Hexadecimal
- 0x711
- Base64
- BxE=
- One's complement
- 63,726 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵αωθʹ
- Mayan (base 20)
- 𝋤·𝋪·𝋩
- Chinese
- 一千八百零九
- Chinese (financial)
- 壹仟捌佰零玖
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,809 = 7
- e — Euler's number (e)
- Digit 1,809 = 1
- φ — Golden ratio (φ)
- Digit 1,809 = 6
- √2 — Pythagoras's (√2)
- Digit 1,809 = 9
- ln 2 — Natural log of 2
- Digit 1,809 = 4
- γ — Euler-Mascheroni (γ)
- Digit 1,809 = 1
Also seen as
UTF-8 encoding: DC 91 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.17.
- Address
- 0.0.7.17
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.7.17
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1809 first appears in π at position 3,801 of the decimal expansion (the 3,801ordinal-suffix:st digit after the integer 3).
Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.