688
688 is a composite number, even, a calendar year.
Historical context — 688 AD
Calendar year
Year 688 (DCLXXXVIII) was a leap year starting on Wednesday of the Julian calendar.
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Historical context — 688 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
- 52
- Started on
-
Sunday
January 1, 688
- Ended on
-
Monday
December 31, 688
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Decade
-
680s
680–689
- Century
-
7th century
601–700
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,338
1338 years before 2026.
In other calendars
- Hebrew
-
4448 / 4449 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
68 / 69 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Earth zodiac:Rat
Sexagenary cycle position 25 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1231 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
66 / 67 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
680 / 681 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
610 / 609 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 3
- Digit sum
- 22
- Digit product
- 384
- Digital root
- 4
- Palindrome
- No
- Bit width
- 10 bits
- Reversed
- 886
- Flips to (rotate 180°)
- 889
- Recamán's sequence
- a(2,248) = 688
- Square (n²)
- 473,344
- Cube (n³)
- 325,660,672
- Divisor count
- 10
- σ(n) — sum of divisors
- 1,364
- φ(n) — Euler's totient
- 336
- Sum of prime factors
- 51
Primality
Prime factorization: 2 4 × 43
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- six hundred eighty-eight
- Ordinal
- 688th
- Roman numeral
- DCLXXXVIII
- Binary
- 1010110000
- Octal
- 1260
- Hexadecimal
- 0x2B0
- Base64
- ArA=
- One's complement
- 64,847 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- χπηʹ
- Mayan (base 20)
- 𝋡·𝋮·𝋨
- Chinese
- 六百八十八
- Chinese (financial)
- 陸佰捌拾捌
Digit at this position in famous constants
- π — Pi (π)
- Digit 688 = 2
- e — Euler's number (e)
- Digit 688 = 1
- φ — Golden ratio (φ)
- Digit 688 = 2
- √2 — Pythagoras's (√2)
- Digit 688 = 0
- ln 2 — Natural log of 2
- Digit 688 = 8
- γ — Euler-Mascheroni (γ)
- Digit 688 = 6
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 688, here are decompositions:
- 5 + 683 = 688
- 11 + 677 = 688
- 29 + 659 = 688
- 41 + 647 = 688
- 47 + 641 = 688
- 71 + 617 = 688
- 89 + 599 = 688
- 101 + 587 = 688
Showing the first eight; more decompositions exist.
UTF-8 encoding: CA B0 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.176.
- Address
- 0.0.2.176
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.176
Unspecified address (0.0.0.0/8) — "this network" placeholder.