680
680 is a composite number, even, a calendar year.
Historical context — 680 AD
Calendar year
Year 680 (DCLXXX) was a leap year starting on Sunday of the Julian calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →
Historical context — 680 BC
Decade
This article concerns the period 689 BC – 680 BC.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →
Year facts
- Year type
-
Leap year
Divisible by 4 and not by 100; February has 29 days.
- Days in year
- 366
- ISO weeks
-
53
Long year: contains 53 ISO weeks.
- Started on
-
Thursday
January 1, 680
- Ended on
-
Friday
December 31, 680
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
680s
680–689
- Century
-
7th century
601–700
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,346
1346 years before 2026.
In other calendars
- Hebrew
-
4440 / 4441 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
60 / 61 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Dragon
Sexagenary cycle position 17 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1223 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
58 / 59 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
672 / 673 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
602 / 601 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 3
- Digit sum
- 14
- Digit product
- 0
- Digital root
- 5
- Palindrome
- No
- Bit width
- 10 bits
- Reversed
- 86
- Flips to (rotate 180°)
- 89
- Recamán's sequence
- a(2,264) = 680
- Square (n²)
- 462,400
- Cube (n³)
- 314,432,000
- Divisor count
- 16
- σ(n) — sum of divisors
- 1,620
- φ(n) — Euler's totient
- 256
- Sum of prime factors
- 28
Primality
Prime factorization: 2 3 × 5 × 17
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- six hundred eighty
- Ordinal
- 680th
- Roman numeral
- DCLXXX
- Binary
- 1010101000
- Octal
- 1250
- Hexadecimal
- 0x2A8
- Base64
- Aqg=
- One's complement
- 64,855 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹 𒌋𒌋
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
- Greek (Milesian)
- χπʹ
- Mayan (base 20)
- 𝋡·𝋮·𝋠
- Chinese
- 六百八十
- Chinese (financial)
- 陸佰捌拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 680 = 3
- e — Euler's number (e)
- Digit 680 = 7
- φ — Golden ratio (φ)
- Digit 680 = 9
- √2 — Pythagoras's (√2)
- Digit 680 = 0
- ln 2 — Natural log of 2
- Digit 680 = 4
- γ — Euler-Mascheroni (γ)
- Digit 680 = 4
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 680, here are decompositions:
- 3 + 677 = 680
- 7 + 673 = 680
- 19 + 661 = 680
- 37 + 643 = 680
- 61 + 619 = 680
- 67 + 613 = 680
- 73 + 607 = 680
- 79 + 601 = 680
Showing the first eight; more decompositions exist.
UTF-8 encoding: CA A8 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.168.
- Address
- 0.0.2.168
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.168
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 680 is an active NANP area code (North American Numbering Plan).
- Primary area
- Syracuse
- Region
- New York
- 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.