1,866
1,866 is a composite number, even, a calendar year.
Notable events — 1866 AD
- Jul 3 Prussia decisively defeats Austria at Königgrätz, paving the way for German unification.
- Jul 27 The first lasting transatlantic telegraph cable is laid.
- Apr 9 The Civil Rights Act of 1866 is enacted over Andrew Johnson's veto.
- Jun 20 Italy joins Prussia against Austria in the Third Italian War of Independence.
- Dec 21 The Fetterman Fight near Fort Phil Kearny kills 81 US soldiers.
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
-
Monday
January 1, 1866
- Ended on
-
Monday
December 31, 1866
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Easter Sunday
-
April 1
Sunday, April 1, 1866
- Decade
-
1860s
1860–1869
- Century
-
19th century
1801–1900
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
160
160 years before 2026.
In other calendars
- Hebrew
-
5626 / 5627 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1282 / 1283 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Fire zodiac:Tiger
Sexagenary cycle position 3 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2409 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1244 / 1245 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1858 / 1859 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1788 / 1787 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 4
- Digit sum
- 21
- Digit product
- 288
- Digital root
- 3
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 6,681
- Flips to (rotate 180°)
- 9,981
- Recamán's sequence
- a(8,012) = 1,866
- Square (n²)
- 3,481,956
- Cube (n³)
- 6,497,329,896
- Divisor count
- 8
- σ(n) — sum of divisors
- 3,744
- φ(n) — Euler's totient
- 620
- Sum of prime factors
- 316
Primality
Prime factorization: 2 × 3 × 311
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand eight hundred sixty-six
- Ordinal
- 1866th
- Roman numeral
- MDCCCLXVI
- Binary
- 11101001010
- Octal
- 3512
- Hexadecimal
- 0x74A
- Base64
- B0o=
- One's complement
- 63,669 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋𒁹 𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵αωξϛʹ
- Mayan (base 20)
- 𝋤·𝋭·𝋦
- Chinese
- 一千八百六十六
- Chinese (financial)
- 壹仟捌佰陸拾陸
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,866 = 2
- e — Euler's number (e)
- Digit 1,866 = 6
- φ — Golden ratio (φ)
- Digit 1,866 = 4
- √2 — Pythagoras's (√2)
- Digit 1,866 = 6
- ln 2 — Natural log of 2
- Digit 1,866 = 0
- γ — Euler-Mascheroni (γ)
- Digit 1,866 = 9
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1866, here are decompositions:
- 5 + 1861 = 1866
- 19 + 1847 = 1866
- 43 + 1823 = 1866
- 79 + 1787 = 1866
- 83 + 1783 = 1866
- 89 + 1777 = 1866
- 107 + 1759 = 1866
- 113 + 1753 = 1866
Showing the first eight; more decompositions exist.
UTF-8 encoding: DD 8A (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.74.
- Address
- 0.0.7.74
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.7.74
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1866 first appears in π at position 3,149 of the decimal expansion (the 3,149ordinal-suffix:th 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.