231
231 is a composite number, odd, a calendar year.
Historical context — 231 AD
Calendar year
Year 231 (CCXXXI) was a common year starting on Saturday of the Julian calendar.
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Historical context — 231 BC
Calendar year
Year 231 BC was a year of the pre-Julian Roman calendar.
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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, 231
- Ended on
-
Saturday
December 31, 231
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
230s
230–239
- Century
-
3rd century
201–300
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,795
1795 years before 2026.
In other calendars
- Hebrew
-
3991 / 3992 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Metal zodiac:Pig
Sexagenary cycle position 48 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
774 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
223 / 224 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
153 / 152 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 × 7 × 11
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- two hundred thirty-one
- Ordinal
- 231st
- Roman numeral
- CCXXXI
- Binary
- 11100111
- Octal
- 347
- Hexadecimal
- 0xE7
- Base64
- 5w==
- One's complement
- 24 (8-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓎆𓎆𓎆𓏺
- Greek (Milesian)
- σλαʹ
- Mayan (base 20)
- 𝋫·𝋫
- Chinese
- 二百三十一
- Chinese (financial)
- 貳佰參拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 231 = 3
- e — Euler's number (e)
- Digit 231 = 8
- φ — Golden ratio (φ)
- Digit 231 = 2
- √2 — Pythagoras's (√2)
- Digit 231 = 1
- ln 2 — Natural log of 2
- Digit 231 = 7
- γ — Euler-Mascheroni (γ)
- Digit 231 = 7
Also seen as
UTF-8 encoding: C3 A7 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.231.
- Address
- 0.0.0.231
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.231
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 231 is an active NANP area code (North American Numbering Plan).
- Primary area
- Traverse City / Muskegon
- Region
- Michigan
- 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.