581
581 is a composite number, odd, a calendar year.
581 (five hundred eighty-one) is an odd 3-digit number. It is a composite number with 4 divisors, and factors as 7 × 83. Written other ways, in Roman numerals it is DLXXXI and in binary, 1001000101.
Interestingness
Historical context — 581 AD
Calendar year
Year 581 (DLXXXI) was a common 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 — 581 BC
Calendar year
The year 581 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, 581
- Ended on
-
Monday
December 31, 581
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
580s
580–589
- Century
-
6th century
501–600
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,445
1445 years before 2026.
In other calendars
- Hebrew
-
4341 / 4342 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Metal zodiac:Ox
Sexagenary cycle position 38 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1124 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
573 / 574 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
503 / 502 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 7 × 83
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√581 = [24; (9, 1, 1, 1, 1, 1, 3, 11, 1, 3, 2, 6, 2, 3, 1, 11, 3, 1, 1, 1, 1, 1, 9, 48)]
Period length 24 — the block in parentheses repeats forever.
Representations
- In words
- five hundred eighty-one
- Ordinal
- 581st
- Roman numeral
- DLXXXI
- Binary
- 1001000101
- Octal
- 1105
- Hexadecimal
- 0x245
- Base64
- AkU=
- One's complement
- 64,954 (16-bit)
- Scientific notation
- 5.81 × 10²
- As a duration
- 581 s = 9 minutes, 41 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- φπαʹ
- Mayan (base 20)
- 𝋡·𝋩·𝋡
- Chinese
- 五百八十一
- Chinese (financial)
- 伍佰捌拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 581 = 3
- e — Euler's number (e)
- Digit 581 = 4
- φ — Golden ratio (φ)
- Digit 581 = 6
- √2 — Pythagoras's (√2)
- Digit 581 = 0
- ln 2 — Natural log of 2
- Digit 581 = 2
- γ — Euler-Mascheroni (γ)
- Digit 581 = 4
Also seen as
UTF-8 encoding: C9 85 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.69.
- Address
- 0.0.2.69
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.69
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 581 is an active NANP area code (North American Numbering Plan).
- Primary area
- Eastern Québec
- Region
- Québec
- Country
- Canada
Most NANP area codes have multiple overlays in dense regions; the primary area listed is the historic/largest population center for this code.
Heard as a frequency, 581 Hz is closest to:
- Concert pitch (A4 = 440 Hz): D5 (587.3 Hz, -19¢)
- Scientific pitch (C4 = 256 Hz): D5 (574.7 Hz, +19¢)
- Baroque pitch (A4 = 415 Hz): D♯5 (586.9 Hz, -17¢)
Related reading
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.