Number
1,891
1,891 is a composite number, odd, a calendar year.
Notable events — 1891 AD
- May 15 Pope Leo XIII issues the encyclical Rerum Novarum on labor and capital.
- Nov 11 Brazil's first republican constitution is officially signed.
- Jan 7 Construction of the Trans-Siberian Railway officially begins.
- Oct 16 The Mizque massacre kills indigenous workers in Bolivia.
- Undated A devastating famine begins in the Volga region of Russia.
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
-
53
Long year: contains 53 ISO weeks.
- Started on
-
Thursday
January 1, 1891
- Ended on
-
Thursday
December 31, 1891
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Easter Sunday
-
March 29
Sunday, March 29, 1891
- Decade
-
1890s
1890–1899
- Century
-
19th century
1801–1900
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
135
135 years before 2026.
In other calendars
- Hebrew
-
5651 / 5652 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1308 / 1309 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Rabbit
Sexagenary cycle position 28 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2434 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1269 / 1270 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1883 / 1884 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1813 / 1812 Saka
Indian national calendar; year starts in March.
- Japanese
-
Meiji 24
Reign-era counting from the start of each emperor's reign.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 19
- Digit product
- 72
- Digital root
- 1
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 1,981
- Flips to (rotate 180°)
- 1,681
- Recamán's sequence
- a(7,962) = 1,891
- Square (n²)
- 3,575,881
- Cube (n³)
- 6,761,990,971
- Divisor count
- 4
- σ(n) — sum of divisors
- 1,984
- φ(n) — Euler's totient
- 1,800
- Sum of prime factors
- 92
Primality
Prime factorization: 31 × 61
Divisors & multiples
Aliquot sum (sum of proper divisors):
93
First multiples
Sums & aliquot sequence
As consecutive integers:
945 + 946
46 + 47 + … + 76
1 + 2 + … + 61
Aliquot sequence:
1,891 → 93 → 35 → 13 → 1 → 0
— terminates at zero
Representations
- In words
- one thousand eight hundred ninety-one
- Ordinal
- 1891st
- Roman numeral
- MDCCCXCI
- Binary
- 11101100011
- Octal
- 3543
- Hexadecimal
- 0x763
- Base64
- B2M=
- One's complement
- 63,644 (16-bit)
In other bases
ternary (3)
2121001
quaternary (4)
131203
quinary (5)
30031
senary (6)
12431
septenary (7)
5341
nonary (9)
2531
undecimal (11)
146a
duodecimal (12)
1117
tridecimal (13)
b26
tetradecimal (14)
991
pentadecimal (15)
861
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋𒁹 𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵αωϟαʹ
- Mayan (base 20)
- 𝋤·𝋮·𝋫
- Chinese
- 一千八百九十一
- Chinese (financial)
- 壹仟捌佰玖拾壹
In other modern scripts
Eastern Arabic
١٨٩١
Devanagari
१८९१
Bengali
১৮৯১
Tamil
௧௮௯௧
Thai
๑๘๙๑
Tibetan
༡༨༩༡
Khmer
១៨៩១
Lao
໑໘໙໑
Burmese
၁၈၉၁
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,891 = 2
- e — Euler's number (e)
- Digit 1,891 = 4
- φ — Golden ratio (φ)
- Digit 1,891 = 5
- √2 — Pythagoras's (√2)
- Digit 1,891 = 0
- ln 2 — Natural log of 2
- Digit 1,891 = 3
- γ — Euler-Mascheroni (γ)
- Digit 1,891 = 2
Also seen as
Unicode codepoint
ݣ
Arabic Letter Keheh With Three Dots Above
U+0763
Other letter (Lo)
UTF-8 encoding: DD A3 (2 bytes).
Hex color
#000763
RGB(0, 7, 99)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.99.
- Address
- 0.0.7.99
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.7.99
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Position in π
The digit sequence 1891 first appears in π at position 3,956 of the decimal expansion (the 3,956ordinal-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.