Number

815

815 is a composite number, odd, a calendar year.

Arithmetic Number Deficient Number Odious Number Pernicious Number Recamán's Sequence Self Number Semiprime Squarefree Year

Historical context — 815 AD

Calendar year

Year 815 (DCCCXV) was a common year starting on Monday of the Julian calendar, the 815th year of the Common Era (CE) and Anno Domini (AD) designations, the 815th year of the 1st millennium, the 15th year of the 9th century, and the 6th year of the 810s decade.

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Historical context — 815 BC

Decade

This article concerns the period 819 BC – 810 BC.

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: 53
Long year: contains 53 ISO weeks.
Started on: Thursday
January 1, 815
Ended on: Thursday
December 31, 815
Friday the 13ths: 3
3 Friday the 13ths this year.
Decade: 810s
810–819
Century: 9th century
801–900
Millennium: 1st millennium
1–1000
Years ago: 1,211
1211 years before 2026.

In other calendars

Hebrew: 4575 / 4576 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 199 / 200 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Wood zodiac:Goat
Sexagenary cycle position 32 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1358 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 193 / 194 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 807 / 808 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 737 / 736 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 14
Digit product: 40
Digital root: 5
Palindrome: No
Bit width: 10 bits
Reversed: 518
Recamán's sequence: a(2,118) = 815
Square (n²): 664,225
Cube (n³): 541,343,375
Divisor count: 4
σ(n) — sum of divisors: 984
φ(n) — Euler's totient: 648
Sum of prime factors: 168

Primality

Prime factorization: 5 × 163

Nearest primes: 811 (−4) · 821 (+6)

Divisors & multiples

All divisors (4)

1 · 5 · 163 · 815

Aliquot sum (sum of proper divisors): 169

Factor pairs (a × b = 815)

1 × 815

5 × 163

First multiples

815 · 1,630 (double) · 2,445 · 3,260 · 4,075 · 4,890 · 5,705 · 6,520 · 7,335 · 8,150

Sums & aliquot sequence

As consecutive integers: 407 + 408 161 + 162 + 163 + 164 + 165 77 + 78 + … + 86

Aliquot sequence: 815 → 169 → 14 → 10 → 8 → 7 → 1 → 0 — terminates at zero

Representations

In words: eight hundred fifteen
Ordinal: 815th
Roman numeral: DCCCXV
Binary: 1100101111
Octal: 1457
Hexadecimal: 0x32F
Base64: Ay8=
One's complement: 64,720 (16-bit)

In other bases

ternary (3) 1010012

quaternary (4) 30233

quinary (5) 11230

senary (6) 3435

septenary (7) 2243

nonary (9) 1105

undecimal (11) 681

duodecimal (12) 57b

tridecimal (13) 4a9

tetradecimal (14) 423

pentadecimal (15) 395

Historical numeral systems

Babylonian (base 60): 𒌋𒁹𒁹𒁹 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ωιεʹ
Mayan (base 20): 𝋢·𝋠·𝋯
Chinese: 八百一十五
Chinese (financial): 捌佰壹拾伍

In other modern scripts

Eastern Arabic ٨١٥ Devanagari ८१५ Bengali ৮১৫ Tamil ௮௧௫ Thai ๘๑๕ Tibetan ༨༡༥ Khmer ៨១៥ Lao ໘໑໕ Burmese ၈၁၅

Digit at this position in famous constants

π — Pi (π): Digit 815 = 9
e — Euler's number (e): Digit 815 = 8
φ — Golden ratio (φ): Digit 815 = 2
√2 — Pythagoras's (√2): Digit 815 = 9
ln 2 — Natural log of 2: Digit 815 = 8
γ — Euler-Mascheroni (γ): Digit 815 = 3

Also seen as

Unicode codepoint

Combining Inverted Breve Below

U+032F

Non-spacing mark (Mn)

UTF-8 encoding: CC AF (2 bytes).

Lookup U+032F on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00032F

RGB(0, 3, 47)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.47.

Address: 0.0.3.47
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.3.47

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

NANP area code 815

The number 815 is an active NANP area code (North American Numbering Plan).

Primary area: Rockford / Joliet
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 815 ↗

Calculator-display word

Type 815 on a seven-segment calculator, flip it 180°, and the display reads:

SIB

A staple of calculator humor since pocket calculators put digits in front of bored students.