521
521 is a prime, odd, a calendar year.
Historical context — 521 AD
Calendar year
Year 521 (DXXI) was a common year starting on Friday of the Julian calendar.
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Historical context — 521 BC
Calendar year
The year 521 BC was a year of the pre-Julian Roman calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback 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
-
Wednesday
January 1, 521
- Ended on
-
Wednesday
December 31, 521
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
520s
520–529
- Century
-
6th century
501–600
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,505
1505 years before 2026.
In other calendars
- Hebrew
-
4281 / 4282 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
-
1064 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
513 / 514 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
443 / 442 Saka
Indian national calendar; year starts in March.
Cultural significance
"I love you too" — partner of 520.
Sourced from Wikipedia (Numerology, Chinese numerology, Gematria, and per-culture articles).
Properties
Primality
521 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- five hundred twenty-one
- Ordinal
- 521st
- Roman numeral
- DXXI
- Binary
- 1000001001
- Octal
- 1011
- Hexadecimal
- 0x209
- Base64
- Agk=
- One's complement
- 65,014 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺
- Greek (Milesian)
- φκαʹ
- Mayan (base 20)
- 𝋡·𝋦·𝋡
- Chinese
- 五百二十一
- Chinese (financial)
- 伍佰貳拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 521 = 0
- e — Euler's number (e)
- Digit 521 = 5
- φ — Golden ratio (φ)
- Digit 521 = 8
- √2 — Pythagoras's (√2)
- Digit 521 = 7
- ln 2 — Natural log of 2
- Digit 521 = 2
- γ — Euler-Mascheroni (γ)
- Digit 521 = 1
Also seen as
UTF-8 encoding: C8 89 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.9.
- Address
- 0.0.2.9
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.9
Unspecified address (0.0.0.0/8) — "this network" placeholder.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.