1,391
1,391 is a composite number, odd, a calendar year.
Historical context — 1391 AD
Calendar year
Year 1391 (MCCCXCI) was a common year starting on Sunday of the Julian calendar.
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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
-
Saturday
January 1, 1391
- Ended on
-
Saturday
December 31, 1391
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
1390s
1390–1399
- Century
-
14th century
1301–1400
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
635
635 years before 2026.
In other calendars
- Hebrew
-
5151 / 5152 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
793 / 794 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Goat
Sexagenary cycle position 8 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1934 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
769 / 770 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1383 / 1384 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1313 / 1312 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 13 × 107
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand three hundred ninety-one
- Ordinal
- 1391st
- Roman numeral
- MCCCXCI
- Binary
- 10101101111
- Octal
- 2557
- Hexadecimal
- 0x56F
- Base64
- BW8=
- One's complement
- 64,144 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹𒁹 𒌋𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵ατϟαʹ
- Mayan (base 20)
- 𝋣·𝋩·𝋫
- Chinese
- 一千三百九十一
- Chinese (financial)
- 壹仟參佰玖拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,391 = 6
- e — Euler's number (e)
- Digit 1,391 = 4
- φ — Golden ratio (φ)
- Digit 1,391 = 1
- √2 — Pythagoras's (√2)
- Digit 1,391 = 2
- ln 2 — Natural log of 2
- Digit 1,391 = 3
- γ — Euler-Mascheroni (γ)
- Digit 1,391 = 2
Also seen as
UTF-8 encoding: D5 AF (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.5.111.
- Address
- 0.0.5.111
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.5.111
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1391 first appears in π at position 23,757 of the decimal expansion (the 23,757ordinal-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.