781
781 is a composite number, odd, a calendar year.
Historical context — 781 AD
Calendar year
Year 781 (DCCLXXXI) was a common year starting on Monday of the Julian calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →
Historical context — 781 BC
Decade
This article concerns the period 789 BC – 780 BC.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →
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
-
53
Long year: contains 53 ISO weeks.
- Started on
-
Thursday
January 1, 781
- Ended on
-
Thursday
December 31, 781
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Decade
-
780s
780–789
- Century
-
8th century
701–800
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,245
1245 years before 2026.
In other calendars
- Hebrew
-
4541 / 4542 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
164 / 165 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
-
1324 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
159 / 160 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
773 / 774 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
703 / 702 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 11 × 71
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- seven hundred eighty-one
- Ordinal
- 781st
- Roman numeral
- DCCLXXXI
- Binary
- 1100001101
- Octal
- 1415
- Hexadecimal
- 0x30D
- Base64
- Aw0=
- One's complement
- 64,754 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ψπαʹ
- Mayan (base 20)
- 𝋡·𝋳·𝋡
- Chinese
- 七百八十一
- Chinese (financial)
- 柒佰捌拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 781 = 1
- e — Euler's number (e)
- Digit 781 = 0
- φ — Golden ratio (φ)
- Digit 781 = 3
- √2 — Pythagoras's (√2)
- Digit 781 = 9
- ln 2 — Natural log of 2
- Digit 781 = 6
- γ — Euler-Mascheroni (γ)
- Digit 781 = 9
Also seen as
UTF-8 encoding: CC 8D (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.13.
- Address
- 0.0.3.13
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.3.13
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 781 is an active NANP area code (North American Numbering Plan).
- Primary area
- Northern suburbs of Boston
- Region
- Massachusetts
- Country
- United States
Most NANP area codes have multiple overlays in dense regions; the primary area listed is the historic/largest population center for this code.