Number

1,291

1,291 is a prime, odd, a calendar year.

Arithmetic Number Chen Prime Deficient Number Odious Number Pernicious Number Prime Recamán's Sequence Sexy Prime Squarefree Twin Prime Year

Notable events — 1291 AD

May 18 Mamluk forces capture Acre, ending the last Crusader stronghold in the Levant.

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, 1291
Ended on: Monday
December 31, 1291
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 1290s
1290–1299
Century: 13th century
1201–1300
Millennium: 2nd millennium
1001–2000
Years ago: 735
735 years before 2026.

In other calendars

Hebrew: 5051 / 5052 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 689 / 691 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: 1834 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 669 / 670 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1283 / 1284 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1213 / 1212 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 4
Digit sum: 13
Digit product: 18
Digital root: 4
Palindrome: No
Bit width: 11 bits
Reversed: 1,921
Recamán's sequence: a(30,466) = 1,291
Square (n²): 1,666,681
Cube (n³): 2,151,685,171
Divisor count: 2
σ(n) — sum of divisors: 1,292
φ(n) — Euler's totient: 1,290

Primality

1,291 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 1291

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 1,291)

1 × 1291

First multiples

1,291 · 2,582 (double) · 3,873 · 5,164 · 6,455 · 7,746 · 9,037 · 10,328 · 11,619 · 12,910

Sums & aliquot sequence

As consecutive integers: 645 + 646

Representations

In words: one thousand two hundred ninety-one
Ordinal: 1291st
Roman numeral: MCCXCI
Binary: 10100001011
Octal: 2413
Hexadecimal: 0x50B
Base64: BQs=
One's complement: 64,244 (16-bit)

In other bases

ternary (3) 1202211

quaternary (4) 110023

quinary (5) 20131

senary (6) 5551

septenary (7) 3523

nonary (9) 1684

undecimal (11) a74

duodecimal (12) 8b7

tridecimal (13) 784

tetradecimal (14) 683

pentadecimal (15) 5b1

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒁹 𒌋𒌋𒌋𒁹
Egyptian hieroglyphic: 𓆼𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ͵ασϟαʹ
Mayan (base 20): 𝋣·𝋤·𝋫
Chinese: 一千二百九十一
Chinese (financial): 壹仟貳佰玖拾壹

In other modern scripts

Eastern Arabic ١٢٩١ Devanagari १२९१ Bengali ১২৯১ Tamil ௧௨௯௧ Thai ๑๒๙๑ Tibetan ༡༢༩༡ Khmer ១២៩១ Lao ໑໒໙໑ Burmese ၁၂၉၁

Digit at this position in famous constants

π — Pi (π): Digit 1,291 = 4
e — Euler's number (e): Digit 1,291 = 1
φ — Golden ratio (φ): Digit 1,291 = 4
√2 — Pythagoras's (√2): Digit 1,291 = 8
ln 2 — Natural log of 2: Digit 1,291 = 2
γ — Euler-Mascheroni (γ): Digit 1,291 = 7

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 1,289 (gap of 2)
Next prime: 1,297 (gap of 6)

Pair status: twin with 1289, sexy with 1297.

Unicode codepoint

Cyrillic Small Letter Komi Nje

U+050B

Lowercase letter (Ll)

UTF-8 encoding: D4 8B (2 bytes).

Lookup U+050B on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00050B

RGB(0, 5, 11)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.5.11.

Address: 0.0.5.11
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.5.11

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

Position in π

The digit sequence 1291 first appears in π at position 7,876 of the decimal expansion (the 7,876ordinal-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.

Look up 1291 on Pi Search ↗