Number

660

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

660 (six hundred sixty) is an even 3-digit number. It is a composite number with 24 divisors, and factors as 2² × 3 × 5 × 11. Its proper divisors sum to 1,356, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is DCLX and in binary, 1010010100.

Abundant Number Arithmetic Number Cube-Free Evil Number Flippable Gapful Number Harshad / Niven Highly Abundant Practical Number Recamán's Sequence Semiperfect Number Year

Interestingness

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9 notable facts · grade A

648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672

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Historical context — 660 AD

Calendar year

Year 660 (DCLX) was a leap year starting on Wednesday of the Julian calendar.

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

Historical context — 660 BC

Calendar year

The year 660 BC was a year of the pre-Julian Roman calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 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, 660
Ended on: Monday
December 31, 660
Friday the 13ths: 3
3 Friday the 13ths this year.
Decade: 660s
660–669
Century: 7th century
601–700
Millennium: 1st millennium
1–1000
Years ago: 1,366
1366 years before 2026.

In other calendars

Hebrew: 4420 / 4421 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 39 / 40 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Monkey
Sexagenary cycle position 57 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1203 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 38 / 39 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 652 / 653 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 582 / 581 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 3
Digit sum: 12
Digit product: 0
Digital root: 3
Palindrome: No
Bit width: 10 bits
Reversed: 66
Flips to (rotate 180°): 99
Recamán's sequence: a(2,304) = 660
Square (n²): 435,600
Cube (n³): 287,496,000
Divisor count: 24
σ(n) — sum of divisors: 2,016
φ(n) — Euler's totient: 160
Sum of prime factors: 23

Primality

Prime factorization: 2 ² × 3 × 5 × 11

Nearest primes: 659 (−1) · 661 (+1)

Divisors & multiples

All divisors (24)

1 · 2 · 3 · 4 · 5 · 6 · 10 · 11 · 12 · 15 · 20 · 22 · 30 · 33 · 44 · 55 · 60 · 66 · 110 · 132 · 165 · 220 · 330 (half) · 660

Aliquot sum (sum of proper divisors): 1,356

Factor pairs (a × b = 660)

1 × 660

2 × 330

3 × 220

4 × 165

5 × 132

6 × 110

10 × 66

11 × 60

12 × 55

15 × 44

20 × 33

22 × 30

First multiples

660 · 1,320 (double) · 1,980 · 2,640 · 3,300 · 3,960 · 4,620 · 5,280 · 5,940 · 6,600

Sums & aliquot sequence

As consecutive integers: 219 + 220 + 221 130 + 131 + 132 + 133 + 134 79 + 80 + … + 86 55 + 56 + … + 65

Aliquot sequence: 660 → 1,356 → 1,836 → 3,204 → 4,986 → 5,856 → 9,768 → 17,592 → 26,448 → 47,952 → 94,586 → 47,296 → 46,684 → 42,524 → 31,900 → 46,220 → 50,884 — unresolved within range

Continued fraction of √n

√660 = [25; (1, 2, 4, 2, 1, 50)]

Period length 6 — the block in parentheses repeats forever.

Representations

In words: six hundred sixty
Ordinal: 660th
Roman numeral: DCLX
Binary: 1010010100
Octal: 1224
Hexadecimal: 0x294
Base64: ApQ=
One's complement: 64,875 (16-bit)
Scientific notation: 6.6 × 10²
As a duration: 660 s = 11 minutes

In other bases

ternary (3) 220110

quaternary (4) 22110

quinary (5) 10120

senary (6) 3020

septenary (7) 1632

nonary (9) 813

undecimal (11) 550

duodecimal (12) 470

tridecimal (13) 3ba

tetradecimal (14) 352

pentadecimal (15) 2e0

As an angle

660° = 1 × 360° + 300°

300° ≈ 5.236 rad

Compass bearing: WNW (west-northwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒁹 ·
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆
Greek (Milesian): χξʹ
Mayan (base 20): 𝋡·𝋭·𝋠
Chinese: 六百六十
Chinese (financial): 陸佰陸拾

In other modern scripts

Eastern Arabic ٦٦٠ Devanagari ६६० Bengali ৬৬০ Tamil ௬௬௦ Thai ๖๖๐ Tibetan ༦༦༠ Khmer ៦៦០ Lao ໖໖໐ Burmese ၆၆၀

Digit at this position in famous constants

π — Pi (π): Digit 660 = 0
e — Euler's number (e): Digit 660 = 2
φ — Golden ratio (φ): Digit 660 = 1
√2 — Pythagoras's (√2): Digit 660 = 3
ln 2 — Natural log of 2: Digit 660 = 2
γ — Euler-Mascheroni (γ): Digit 660 = 5

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 660, here are decompositions:

7 + 653 = 660
13 + 647 = 660
17 + 643 = 660
19 + 641 = 660
29 + 631 = 660
41 + 619 = 660
43 + 617 = 660
47 + 613 = 660

Showing the first eight; more decompositions exist.

Unicode codepoint

Latin Letter Glottal Stop

U+0294

Other letter (Lo)

UTF-8 encoding: CA 94 (2 bytes).

Lookup U+0294 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000294

RGB(0, 2, 148)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.148.

Address: 0.0.2.148
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.2.148

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

NANP area code 660

The number 660 is an active NANP area code (North American Numbering Plan).

Primary area: Sedalia / Marshall
Region: Missouri
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.

Look up area code 660 ↗

Musical pitch

Heard as a frequency, 660 Hz is closest to:

Concert pitch (A4 = 440 Hz): E5 (659.3 Hz, +2¢)
Scientific pitch (C4 = 256 Hz): E5 (645.1 Hz, +40¢)
Baroque pitch (A4 = 415 Hz): F5 (658.8 Hz, +3¢)