Number

891

891 is a composite number, odd, a calendar year.

Deficient Number Evil Number Flippable Gapful Number Recamán's Sequence Year

Historical context — 891 AD

Calendar year

Year 891 (DCCCXCI) was a common year starting on Friday of the Julian calendar.

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Historical context — 891 BC

Decade

This article concerns the period 899 BC – 890 BC.

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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: Monday
January 1, 891
Ended on: Monday
December 31, 891
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 890s
890–899
Century: 9th century
801–900
Millennium: 1st millennium
1–1000
Years ago: 1,135
1135 years before 2026.

In other calendars

Hebrew: 4651 / 4652 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 277 / 278 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Pig
Sexagenary cycle position 48 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1434 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 269 / 270 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 883 / 884 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 813 / 812 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 18
Digit product: 72
Digital root: 9
Palindrome: No
Bit width: 10 bits
Reversed: 198
Flips to (rotate 180°): 168
Recamán's sequence: a(465) = 891
Square (n²): 793,881
Cube (n³): 707,347,971
Divisor count: 10
σ(n) — sum of divisors: 1,452
φ(n) — Euler's totient: 540
Sum of prime factors: 23

Primality

Prime factorization: 3 ⁴ × 11

Nearest primes: 887 (−4) · 907 (+16)

Divisors & multiples

All divisors (10)

1 · 3 · 9 · 11 · 27 · 33 · 81 · 99 · 297 · 891

Aliquot sum (sum of proper divisors): 561

Factor pairs (a × b = 891)

1 × 891

3 × 297

9 × 99

11 × 81

27 × 33

First multiples

891 · 1,782 (double) · 2,673 · 3,564 · 4,455 · 5,346 · 6,237 · 7,128 · 8,019 · 8,910

Sums & aliquot sequence

As consecutive integers: 445 + 446 296 + 297 + 298 146 + 147 + 148 + 149 + 150 + 151 95 + 96 + … + 103

Aliquot sequence: 891 → 561 → 303 → 105 → 87 → 33 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Representations

In words: eight hundred ninety-one
Ordinal: 891st
Roman numeral: DCCCXCI
Binary: 1101111011
Octal: 1573
Hexadecimal: 0x37B
Base64: A3s=
One's complement: 64,644 (16-bit)

In other bases

ternary (3) 1020000

quaternary (4) 31323

quinary (5) 12031

senary (6) 4043

septenary (7) 2412

nonary (9) 1200

undecimal (11) 740

duodecimal (12) 623

tridecimal (13) 537

tetradecimal (14) 479

pentadecimal (15) 3e6

Historical numeral systems

Babylonian (base 60): 𒌋𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ωϟαʹ
Mayan (base 20): 𝋢·𝋤·𝋫
Chinese: 八百九十一
Chinese (financial): 捌佰玖拾壹

In other modern scripts

Eastern Arabic ٨٩١ Devanagari ८९१ Bengali ৮৯১ Tamil ௮௯௧ Thai ๘๙๑ Tibetan ༨༩༡ Khmer ៨៩១ Lao ໘໙໑ Burmese ၈၉၁

Digit at this position in famous constants

π — Pi (π): Digit 891 = 7
e — Euler's number (e): Digit 891 = 9
φ — Golden ratio (φ): Digit 891 = 9
√2 — Pythagoras's (√2): Digit 891 = 8
ln 2 — Natural log of 2: Digit 891 = 5
γ — Euler-Mascheroni (γ): Digit 891 = 9

Also seen as

Unicode codepoint

Greek Small Reversed Lunate Sigma Symbol

U+037B

Lowercase letter (Ll)

UTF-8 encoding: CD BB (2 bytes).

Lookup U+037B on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00037B

RGB(0, 3, 123)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.123.

Address: 0.0.3.123
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.3.123

Unspecified address (0.0.0.0/8) — "this network" placeholder.