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Number

331

331 is a prime, odd, a calendar year.

Arithmetic Number Deficient Number Happy Number Odious Number Pernicious Number Prime Recamán's Sequence Sexy Prime Squarefree Year

Historical context — 331 AD

Calendar year

Year 331 (CCCXXXI) was a common year starting on Friday of the Julian calendar.

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

Notable events — 331 BC

Oct 1 Alexander decisively defeats Darius III at Gaugamela, breaking the Persian Empire.

Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0

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: 53
Long year: contains 53 ISO weeks.
Started on: Thursday
January 1, 331
Ended on: Thursday
December 31, 331
Friday the 13ths: 3
3 Friday the 13ths this year.
Decade: 330s
330–339
Century: 4th century
301–400
Millennium: 1st millennium
1–1000
Years ago: 1,695
1695 years before 2026.

In other calendars

Hebrew: 4091 / 4092 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Metal zodiac:Rabbit
Sexagenary cycle position 28 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 874 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 323 / 324 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 253 / 252 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 7
Digit product: 9
Digital root: 7
Palindrome: No
Bit width: 9 bits
Reversed: 133
Recamán's sequence: a(586) = 331
Square (n²): 109,561
Cube (n³): 36,264,691
Divisor count: 2
σ(n) — sum of divisors: 332
φ(n) — Euler's totient: 330

Primality

331 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 331

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 331)

1 × 331

First multiples

331 · 662 (double) · 993 · 1,324 · 1,655 · 1,986 · 2,317 · 2,648 · 2,979 · 3,310

Sums & aliquot sequence

As consecutive integers: 165 + 166

Representations

In words: three hundred thirty-one
Ordinal: 331st
Roman numeral: CCCXXXI
Binary: 101001011
Octal: 513
Hexadecimal: 0x14B
Base64: AUs=
One's complement: 65,204 (16-bit)

In other bases

ternary (3) 110021

quaternary (4) 11023

quinary (5) 2311

senary (6) 1311

septenary (7) 652

nonary (9) 407

undecimal (11) 281

duodecimal (12) 237

tridecimal (13) 1c6

tetradecimal (14) 199

pentadecimal (15) 171

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒁹
Egyptian hieroglyphic: 𓍢𓍢𓍢𓎆𓎆𓎆𓏺
Greek (Milesian): τλαʹ
Mayan (base 20): 𝋰·𝋫
Chinese: 三百三十一
Chinese (financial): 參佰參拾壹

In other modern scripts

Eastern Arabic ٣٣١ Devanagari ३३१ Bengali ৩৩১ Tamil ௩௩௧ Thai ๓๓๑ Tibetan ༣༣༡ Khmer ៣៣១ Lao ໓໓໑ Burmese ၃၃၁

Digit at this position in famous constants

π — Pi (π): Digit 331 = 0
e — Euler's number (e): Digit 331 = 0
φ — Golden ratio (φ): Digit 331 = 5
√2 — Pythagoras's (√2): Digit 331 = 5
ln 2 — Natural log of 2: Digit 331 = 4
γ — Euler-Mascheroni (γ): Digit 331 = 0

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 317 (gap of 14)
Next prime: 337 (gap of 6)

Pair status: sexy with 337.

Unicode codepoint

ŋ

Latin Small Letter Eng

U+014B

Lowercase letter (Ll)

UTF-8 encoding: C5 8B (2 bytes).

Lookup U+014B on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00014B

RGB(0, 1, 75)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.1.75.

Address: 0.0.1.75
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.1.75

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

NANP area code 331

The number 331 is an active NANP area code (North American Numbering Plan).

Primary area: Western suburbs of Chicago
Region: Illinois
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 331 ↗