number.wiki

Number

687

687 is a composite number, odd, a calendar year.

687 (six hundred eighty-seven) is an odd 3-digit number. It is a composite number with 4 divisors, and factors as 3 × 229. Written other ways, in Roman numerals it is DCLXXXVII and in binary, 1010101111.

Arithmetic Number Cube-Free Deficient Number Odious Number Pernicious Number Recamán's Sequence Semiprime Squarefree Year

Interestingness

★ ★ ★ ☆ ☆

5 notable facts · grade C

675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699

less more

Historical context — 687 AD

Calendar year

Year 687 (DCLXXXVII) was a common year starting on Tuesday of the Julian calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →

Historical context — 687 BC

Decade

This article concerns the period 689 BC – 680 BC.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 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: 52
Started on: Saturday
January 1, 687
Ended on: Saturday
December 31, 687
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 680s
680–689
Century: 7th century
601–700
Millennium: 1st millennium
1–1000
Years ago: 1,339
1339 years before 2026.

In other calendars

Hebrew: 4447 / 4448 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 67 / 68 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Fire zodiac:Pig
Sexagenary cycle position 24 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1230 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 65 / 66 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 679 / 680 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 609 / 608 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 21
Digit product: 336
Digital root: 3
Palindrome: No
Bit width: 10 bits
Reversed: 786
Recamán's sequence: a(2,250) = 687
Square (n²): 471,969
Cube (n³): 324,242,703
Divisor count: 4
σ(n) — sum of divisors: 920
φ(n) — Euler's totient: 456
Sum of prime factors: 232

Primality

Prime factorization: 3 × 229

Nearest primes: 683 (−4) · 691 (+4)

Divisors & multiples

All divisors (4)

1 · 3 · 229 · 687

Aliquot sum (sum of proper divisors): 233

Factor pairs (a × b = 687)

1 × 687

3 × 229

First multiples

687 · 1,374 (double) · 2,061 · 2,748 · 3,435 · 4,122 · 4,809 · 5,496 · 6,183 · 6,870

Sums & aliquot sequence

As consecutive integers: 343 + 344 228 + 229 + 230 112 + 113 + 114 + 115 + 116 + 117

Aliquot sequence: 687 → 233 → 1 → 0 — terminates at zero

Continued fraction of √n

√687 = [26; (4, 1, 2, 1, 16, 1, 2, 1, 4, 52)]

Period length 10 — the block in parentheses repeats forever.

Representations

In words: six hundred eighty-seven
Ordinal: 687th
Roman numeral: DCLXXXVII
Binary: 1010101111
Octal: 1257
Hexadecimal: 0x2AF
Base64: Aq8=
One's complement: 64,848 (16-bit)
Scientific notation: 6.87 × 10²
As a duration: 687 s = 11 minutes, 27 seconds

In other bases

ternary (3) 221110

quaternary (4) 22233

quinary (5) 10222

senary (6) 3103

septenary (7) 2001

nonary (9) 843

undecimal (11) 575

duodecimal (12) 493

tridecimal (13) 40b

tetradecimal (14) 371

pentadecimal (15) 30c

Palindromic in base 11

As an angle

687° = 1 × 360° + 327°

327° ≈ 5.707 rad

Compass bearing: NNW (north-northwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒁹 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): χπζʹ
Mayan (base 20): 𝋡·𝋮·𝋧
Chinese: 六百八十七
Chinese (financial): 陸佰捌拾柒

In other modern scripts

Eastern Arabic ٦٨٧ Devanagari ६८७ Bengali ৬৮৭ Tamil ௬௮௭ Thai ๖๘๗ Tibetan ༦༨༧ Khmer ៦៨៧ Lao ໖໘໗ Burmese ၆၈၇

Digit at this position in famous constants

π — Pi (π): Digit 687 = 9
e — Euler's number (e): Digit 687 = 6
φ — Golden ratio (φ): Digit 687 = 5
√2 — Pythagoras's (√2): Digit 687 = 7
ln 2 — Natural log of 2: Digit 687 = 0
γ — Euler-Mascheroni (γ): Digit 687 = 8

Also seen as

Unicode codepoint

ʯ

Latin Small Letter Turned H With Fishhook And Tail

U+02AF

Lowercase letter (Ll)

UTF-8 encoding: CA AF (2 bytes).

Lookup U+02AF on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0002AF

RGB(0, 2, 175)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.175.

Address: 0.0.2.175
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.2.175

Unspecified address (0.0.0.0/8) — "this network" placeholder.

Musical pitch

Heard as a frequency, 687 Hz is closest to:

Concert pitch (A4 = 440 Hz): F5 (698.5 Hz, -29¢)
Scientific pitch (C4 = 256 Hz): F5 (683.4 Hz, +9¢)
Baroque pitch (A4 = 415 Hz): F♯5 (697.9 Hz, -27¢)

Related reading

Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.