551
551 is a composite number, odd, a calendar year.
551 (five hundred fifty-one) is an odd 3-digit number. It is a composite number with 4 divisors, and factors as 19 × 29. Written other ways, in Roman numerals it is DLI and in binary, 1000100111.
Interestingness
Historical context — 551 AD
Calendar year
Year 551 (DLI) was a common year starting on Sunday of the Julian calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →
Notable events — 551 BC
- Undated Traditional birth year of Confucius.
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
- 52
- Started on
-
Friday
January 1, 551
- Ended on
-
Friday
December 31, 551
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
550s
550–559
- Century
-
6th century
501–600
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,475
1475 years before 2026.
In other calendars
- Hebrew
-
4311 / 4312 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Metal zodiac:Goat
Sexagenary cycle position 8 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1094 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
543 / 544 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
473 / 472 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 19 × 29
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√551 = [23; (2, 8, 1, 8, 2, 46)]
Period length 6 — the block in parentheses repeats forever.
Representations
- In words
- five hundred fifty-one
- Ordinal
- 551st
- Roman numeral
- DLI
- Binary
- 1000100111
- Octal
- 1047
- Hexadecimal
- 0x227
- Base64
- Aic=
- One's complement
- 64,984 (16-bit)
- Scientific notation
- 5.51 × 10²
- As a duration
- 551 s = 9 minutes, 11 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- φναʹ
- Mayan (base 20)
- 𝋡·𝋧·𝋫
- Chinese
- 五百五十一
- Chinese (financial)
- 伍佰伍拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 551 = 8
- e — Euler's number (e)
- Digit 551 = 5
- φ — Golden ratio (φ)
- Digit 551 = 4
- √2 — Pythagoras's (√2)
- Digit 551 = 0
- ln 2 — Natural log of 2
- Digit 551 = 1
- γ — Euler-Mascheroni (γ)
- Digit 551 = 2
Also seen as
UTF-8 encoding: C8 A7 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.39.
- Address
- 0.0.2.39
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.39
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 551 is an active NANP area code (North American Numbering Plan).
- Primary area
- Jersey City / Hackensack
- Region
- New Jersey
- 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.
Heard as a frequency, 551 Hz is closest to:
- Concert pitch (A4 = 440 Hz): C♯5 (554.4 Hz, -11¢)
- Scientific pitch (C4 = 256 Hz): C♯5 (542.4 Hz, +27¢)
- Baroque pitch (A4 = 415 Hz): D5 (554 Hz, -9¢)
On an ingredients label, E551 is Silicon dioxide, an acidity regulator or anti-caking agent — an anti-caking agent that keeps powders free-flowing.
Related reading
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.