1,381
1,381 is a prime, odd, a calendar year.
1,381 (one thousand three hundred eighty-one) is an odd 4-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in Roman numerals it is MCCCLXXXI and in binary, 10101100101.
Interestingness
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
Primality
1,381 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√1,381 = [37; (6, 5, 1, 1, 4, 2, 2, 3, 3, 4, 14, 1, 1, 1, 2, 1, 1, 2, 1, 24, 18, 1, 1, 5, …)]
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)
- Scientific notation
- 1.381 × 10³
- As a duration
- 1,381 s = 23 minutes, 1 second
As an angle
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
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
UTF-8 encoding: D5 A5 (2 bytes).
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.
Heard as a frequency, 1,381 Hz is closest to:
- Concert pitch (A4 = 440 Hz): F6 (1396.9 Hz, -20¢)
- Scientific pitch (C4 = 256 Hz): F6 (1366.9 Hz, +18¢)
- Baroque pitch (A4 = 415 Hz): F♯6 (1395.9 Hz, -19¢)
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.
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.