Number

1,809

1,809 is a composite number, odd, a calendar year.

1,809 (one thousand eight hundred nine) is an odd 4-digit number. It is a composite number with 8 divisors, and factors as 3³ × 67. Written other ways, in Roman numerals it is MDCCCIX and in binary, 11100010001.

Arithmetic Number Deficient Number Flippable Odious Number Pernicious Number Recamán's Sequence Year

Interestingness

★ ☆ ☆ ☆ ☆

3 notable facts · grade F

1,797 1,798 1,799 1,800 1,801 1,802 1,803 1,804 1,805 1,806 1,807 1,808 1,809 1,810 1,811 1,812 1,813 1,814 1,815 1,816 1,817 1,818 1,819 1,820 1,821

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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

Nearest primes: 1,801 (−8) · 1,811 (+2)

Divisors & multiples

All divisors (8)

1 · 3 · 9 · 27 · 67 · 201 · 603 · 1809

Aliquot sum (sum of proper divisors): 911

Factor pairs (a × b = 1,809)

1 × 1809

3 × 603

9 × 201

27 × 67

First multiples

1,809 · 3,618 (double) · 5,427 · 7,236 · 9,045 · 10,854 · 12,663 · 14,472 · 16,281 · 18,090

Sums & aliquot sequence

As consecutive integers: 904 + 905 602 + 603 + 604 299 + 300 + 301 + 302 + 303 + 304 197 + 198 + … + 205

Aliquot sequence: 1,809 → 911 → 1 → 0 — terminates at zero

Continued fraction of √n

√1,809 = [42; (1, 1, 7, 4, 2, 1, 9, 1, 16, 9, 2, 1, 1, 4, 1, 2, 1, 1, 2, 1, 1, 2, 1, 4, …)]

Period length 38 — the block in parentheses repeats forever.

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)
Scientific notation: 1.809 × 10³
As a duration: 1,809 s = 30 minutes, 9 seconds

In other bases

ternary (3) 2111000

quaternary (4) 130101

quinary (5) 24214

senary (6) 12213

septenary (7) 5163

nonary (9) 2430

undecimal (11) 13a5

duodecimal (12) 1069

tridecimal (13) a92

tetradecimal (14) 933

pentadecimal (15) 809

As an angle

1,809° = 5 × 360° + 9°

9° ≈ 0.157 rad

Compass bearing: N (north)

Why does a circle have 360 degrees? →

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

In other modern scripts

Eastern Arabic ١٨٠٩ Devanagari १८०९ Bengali ১৮০৯ Tamil ௧௮௦௯ Thai ๑๘๐๙ Tibetan ༡༨༠༩ Khmer ១៨០៩ Lao ໑໘໐໙ Burmese ၁၈၀၉

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

Unicode codepoint

Syriac Letter Superscript Alaph

U+0711

Non-spacing mark (Mn)

UTF-8 encoding: DC 91 (2 bytes).

Lookup U+0711 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000711

RGB(0, 7, 17)

IPv4 address

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.

Musical pitch

Heard as a frequency, 1,809 Hz is closest to:

Concert pitch (A4 = 440 Hz): A6 (1760 Hz, +48¢ — about midway to A♯6)
Scientific pitch (C4 = 256 Hz): A♯6 (1824.6 Hz, -15¢)
Baroque pitch (A4 = 415 Hz): A♯6 (1758.7 Hz, +49¢ — about midway to B6)

Position in π

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.

Look up 1809 on Pi Search ↗