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Number

1,381

1,381 is a prime, odd, a calendar year.

Arithmetic Number Chen Prime Deficient Number Emirp Evil Number Prime Pythagorean Prime Recamán's Sequence Squarefree Year

Notable events — 1381 AD

Jun 15 Wat Tyler is killed during the Peasants' Revolt in England.

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, 1381
Ended on: Monday
December 31, 1381
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 1380s
1380–1389
Century: 14th century
1301–1400
Millennium: 2nd millennium
1001–2000
Years ago: 645
645 years before 2026.

In other calendars

Hebrew: 5141 / 5142 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 782 / 783 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Rooster
Sexagenary cycle position 58 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1924 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 759 / 760 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1373 / 1374 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1303 / 1302 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 4
Digit sum: 13
Digit product: 24
Digital root: 4
Palindrome: No
Bit width: 11 bits
Reversed: 1,831
Recamán's sequence: a(8,366) = 1,381
Square (n²): 1,907,161
Cube (n³): 2,633,789,341
Divisor count: 2
σ(n) — sum of divisors: 1,382
φ(n) — Euler's totient: 1,380

Primality

1,381 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 1381

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 1,381)

1 × 1381

First multiples

1,381 · 2,762 (double) · 4,143 · 5,524 · 6,905 · 8,286 · 9,667 · 11,048 · 12,429 · 13,810

Sums & aliquot sequence

As a sum of two squares: 15² + 34²

As consecutive integers: 690 + 691

Representations

In words: one thousand three hundred eighty-one
Ordinal: 1381st
Roman numeral: MCCCLXXXI
Binary: 10101100101
Octal: 2545
Hexadecimal: 0x565
Base64: BWU=
One's complement: 64,154 (16-bit)

In other bases

ternary (3) 1220011

quaternary (4) 111211

quinary (5) 21011

senary (6) 10221

septenary (7) 4012

nonary (9) 1804

undecimal (11) 1046

duodecimal (12) 971

tridecimal (13) 823

tetradecimal (14) 709

pentadecimal (15) 621

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒁹𒁹𒁹 𒁹
Egyptian hieroglyphic: 𓆼𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ͵ατπαʹ
Mayan (base 20): 𝋣·𝋩·𝋡
Chinese: 一千三百八十一
Chinese (financial): 壹仟參佰捌拾壹

In other modern scripts

Eastern Arabic ١٣٨١ Devanagari १३८१ Bengali ১৩৮১ Tamil ௧௩௮௧ Thai ๑๓๘๑ Tibetan ༡༣༨༡ Khmer ១៣៨១ Lao ໑໓໘໑ Burmese ၁၃၈၁

Digit at this position in famous constants

π — Pi (π): Digit 1,381 = 3
e — Euler's number (e): Digit 1,381 = 4
φ — Golden ratio (φ): Digit 1,381 = 2
√2 — Pythagoras's (√2): Digit 1,381 = 3
ln 2 — Natural log of 2: Digit 1,381 = 1
γ — Euler-Mascheroni (γ): Digit 1,381 = 8

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 1,373 (gap of 8)
Next prime: 1,399 (gap of 18)

Unicode codepoint

ե

Armenian Small Letter Ech

U+0565

Lowercase letter (Ll)

UTF-8 encoding: D5 A5 (2 bytes).

Lookup U+0565 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000565

RGB(0, 5, 101)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.5.101.

Address: 0.0.5.101
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.5.101

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

Position in π

The digit sequence 1381 first appears in π at position 6,278 of the decimal expansion (the 6,278ordinal-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 1381 on Pi Search ↗