Number

690

690 is a composite number, even, a calendar year.

690 (six hundred ninety) is an even 3-digit number. It is a composite number with 16 divisors, and factors as 2 × 3 × 5 × 23. Its proper divisors sum to 1,038, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is DCXC and in binary, 1010110010.

Abundant Number Arithmetic Number Cube-Free Flippable Harshad / Niven Odious Number Pernicious Number Practical Number Recamán's Sequence Semiperfect Number Smith Number Squarefree Year

Interestingness

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9 notable facts · grade A

678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702

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Historical context — 690 AD

Calendar year

Year 690 (DCXC) was a common year starting on Saturday of the Julian calendar.

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

Historical context — 690 BC

Decade

This article concerns the period 699 BC – 690 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: Wednesday
January 1, 690
Ended on: Wednesday
December 31, 690
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 690s
690–699
Century: 7th century
601–700
Millennium: 1st millennium
1–1000
Years ago: 1,336
1336 years before 2026.

In other calendars

Hebrew: 4450 / 4451 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 70 / 71 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Tiger
Sexagenary cycle position 27 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1233 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 68 / 69 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 682 / 683 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 612 / 611 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 3
Digit sum: 15
Digit product: 0
Digital root: 6
Palindrome: No
Bit width: 10 bits
Reversed: 96
Flips to (rotate 180°): 69
Recamán's sequence: a(2,244) = 690
Square (n²): 476,100
Cube (n³): 328,509,000
Divisor count: 16
σ(n) — sum of divisors: 1,728
φ(n) — Euler's totient: 176
Sum of prime factors: 33

Primality

Prime factorization: 2 × 3 × 5 × 23

Nearest primes: 683 (−7) · 691 (+1)

Divisors & multiples

All divisors (16)

1 · 2 · 3 · 5 · 6 · 10 · 15 · 23 · 30 · 46 · 69 · 115 · 138 · 230 · 345 (half) · 690

Aliquot sum (sum of proper divisors): 1,038

Factor pairs (a × b = 690)

1 × 690

2 × 345

3 × 230

5 × 138

6 × 115

10 × 69

15 × 46

23 × 30

First multiples

690 · 1,380 (double) · 2,070 · 2,760 · 3,450 · 4,140 · 4,830 · 5,520 · 6,210 · 6,900

Sums & aliquot sequence

As consecutive integers: 229 + 230 + 231 171 + 172 + 173 + 174 136 + 137 + 138 + 139 + 140 52 + 53 + … + 63

Aliquot sequence: 690 → 1,038 → 1,050 → 1,926 → 2,286 → 2,706 → 3,342 → 3,354 → 4,038 → 4,050 → 7,203 → 4,001 → 1 → 0 — terminates at zero

Continued fraction of √n

√690 = [26; (3, 1, 2, 1, 3, 52)]

Period length 6 — the block in parentheses repeats forever.

Representations

In words: six hundred ninety
Ordinal: 690th
Roman numeral: DCXC
Binary: 1010110010
Octal: 1262
Hexadecimal: 0x2B2
Base64: ArI=
One's complement: 64,845 (16-bit)
Scientific notation: 6.9 × 10²
As a duration: 690 s = 11 minutes, 30 seconds

In other bases

ternary (3) 221120

quaternary (4) 22302

quinary (5) 10230

senary (6) 3110

septenary (7) 2004

nonary (9) 846

undecimal (11) 578

duodecimal (12) 496

tridecimal (13) 411

tetradecimal (14) 374

pentadecimal (15) 310

Palindromic in base 16

As an angle

690° = 1 × 360° + 330°

330° ≈ 5.76 rad

Compass bearing: NNW (north-northwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒁹 𒌋𒌋𒌋
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
Greek (Milesian): χϟʹ
Mayan (base 20): 𝋡·𝋮·𝋪
Chinese: 六百九十
Chinese (financial): 陸佰玖拾

In other modern scripts

Eastern Arabic ٦٩٠ Devanagari ६९० Bengali ৬৯০ Tamil ௬௯௦ Thai ๖๙๐ Tibetan ༦༩༠ Khmer ៦៩០ Lao ໖໙໐ Burmese ၆၉၀

Digit at this position in famous constants

π — Pi (π): Digit 690 = 7
e — Euler's number (e): Digit 690 = 3
φ — Golden ratio (φ): Digit 690 = 4
√2 — Pythagoras's (√2): Digit 690 = 0
ln 2 — Natural log of 2: Digit 690 = 9
γ — Euler-Mascheroni (γ): Digit 690 = 8

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 690, here are decompositions:

7 + 683 = 690
13 + 677 = 690
17 + 673 = 690
29 + 661 = 690
31 + 659 = 690
37 + 653 = 690
43 + 647 = 690
47 + 643 = 690

Showing the first eight; more decompositions exist.

Unicode codepoint

Modifier Letter Small J

U+02B2

Modifier letter (Lm)

UTF-8 encoding: CA B2 (2 bytes).

Lookup U+02B2 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0002B2

RGB(0, 2, 178)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.178.

Address: 0.0.2.178
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.2.178

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

Musical pitch

Heard as a frequency, 690 Hz is closest to:

Concert pitch (A4 = 440 Hz): F5 (698.5 Hz, -21¢)
Scientific pitch (C4 = 256 Hz): F5 (683.4 Hz, +17¢)
Baroque pitch (A4 = 415 Hz): F♯5 (697.9 Hz, -20¢)