Number

390

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

390 (three hundred ninety) is an even 3-digit number. It is a composite number with 16 divisors, and factors as 2 × 3 × 5 × 13. Its proper divisors sum to 618, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is CCCXC and in binary, 110000110.

Abundant Number Arithmetic Number Cube-Free Evil Number Gapful Number Practical Number Preferred Number Recamán's Sequence Semiperfect Number Squarefree Year

Interestingness

★ ★ ★ ★ ★

8 notable facts · grade A

378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402

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Historical context — 390 AD

Calendar year

Year 390 (CCCXC) 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 — 390 BC

Calendar year

Year 390 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: 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: Monday
January 1, 390
Ended on: Monday
December 31, 390
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 390s
390–399
Century: 4th century
301–400
Millennium: 1st millennium
1–1000
Years ago: 1,636
1636 years before 2026.

In other calendars

Hebrew: 4150 / 4151 AM
Rosh Hashanah falls in September/October.
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: 933 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 382 / 383 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 312 / 311 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: 9 bits
Reversed: 93
Recamán's sequence: a(2,472) = 390
Square (n²): 152,100
Cube (n³): 59,319,000
Divisor count: 16
σ(n) — sum of divisors: 1,008
φ(n) — Euler's totient: 96
Sum of prime factors: 23

Primality

Prime factorization: 2 × 3 × 5 × 13

Nearest primes: 389 (−1) · 397 (+7)

Divisors & multiples

All divisors (16)

1 · 2 · 3 · 5 · 6 · 10 · 13 · 15 · 26 · 30 · 39 · 65 · 78 · 130 · 195 (half) · 390

Aliquot sum (sum of proper divisors): 618

Factor pairs (a × b = 390)

1 × 390

2 × 195

3 × 130

5 × 78

6 × 65

10 × 39

13 × 30

15 × 26

First multiples

390 · 780 (double) · 1,170 · 1,560 · 1,950 · 2,340 · 2,730 · 3,120 · 3,510 · 3,900

Sums & aliquot sequence

As consecutive integers: 129 + 130 + 131 96 + 97 + 98 + 99 76 + 77 + 78 + 79 + 80 27 + 28 + … + 38

Aliquot sequence: 390 → 618 → 630 → 1,242 → 1,638 → 2,730 → 5,334 → 6,954 → 7,926 → 7,938 → 12,753 → 7,267 → 785 → 163 → 1 → 0 — terminates at zero

Continued fraction of √n

√390 = [19; (1, 2, 1, 38)]

Period length 4 — the block in parentheses repeats forever.

Representations

In words: three hundred ninety
Ordinal: 390th
Roman numeral: CCCXC
Binary: 110000110
Octal: 606
Hexadecimal: 0x186
Base64: AYY=
One's complement: 65,145 (16-bit)
Scientific notation: 3.9 × 10²
As a duration: 390 s = 6 minutes, 30 seconds

In other bases

ternary (3) 112110

quaternary (4) 12012

quinary (5) 3030

senary (6) 1450

septenary (7) 1065

nonary (9) 473

undecimal (11) 325

duodecimal (12) 286

tridecimal (13) 240

tetradecimal (14) 1dc

pentadecimal (15) 1b0

Palindromic in base 8

As an angle

390° = 1 × 360° + 30°

30° ≈ 0.524 rad

Compass bearing: NNE (north-northeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋
Egyptian hieroglyphic: 𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
Greek (Milesian): τϟʹ
Mayan (base 20): 𝋳·𝋪
Chinese: 三百九十
Chinese (financial): 參佰玖拾

In other modern scripts

Eastern Arabic ٣٩٠ Devanagari ३९० Bengali ৩৯০ Tamil ௩௯௦ Thai ๓๙๐ Tibetan ༣༩༠ Khmer ៣៩០ Lao ໓໙໐ Burmese ၃၉၀

Digit at this position in famous constants

π — Pi (π): Digit 390 = 5
e — Euler's number (e): Digit 390 = 7
φ — Golden ratio (φ): Digit 390 = 1
√2 — Pythagoras's (√2): Digit 390 = 0
ln 2 — Natural log of 2: Digit 390 = 8
γ — Euler-Mascheroni (γ): Digit 390 = 5

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 390, here are decompositions:

7 + 383 = 390
11 + 379 = 390
17 + 373 = 390
23 + 367 = 390
31 + 359 = 390
37 + 353 = 390
41 + 349 = 390
43 + 347 = 390

Showing the first eight; more decompositions exist.

Unicode codepoint

Latin Capital Letter Open O

U+0186

Uppercase letter (Lu)

UTF-8 encoding: C6 86 (2 bytes).

Lookup U+0186 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000186

RGB(0, 1, 134)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.1.134.

Address: 0.0.1.134
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.1.134

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

Musical pitch

Heard as a frequency, 390 Hz is closest to:

Concert pitch (A4 = 440 Hz): G4 (392 Hz, -9¢)
Scientific pitch (C4 = 256 Hz): G4 (383.6 Hz, +29¢)
Baroque pitch (A4 = 415 Hz): G♯4 (391.7 Hz, -8¢)