870
870 is a composite number, even, a calendar year.
Historical context — 870 AD
Calendar year
Year 870 (DCCCLXX) was a common year starting on Sunday of the Julian calendar, the 870th year of the Common Era (CE) and Anno Domini (AD) designations, the 870th year of the 1st millennium, the 70th year of the 9th century, and the 1st year of the 870s decade.
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Historical context — 870 BC
Decade
This article concerns the period 879 BC – 870 BC.
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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
-
Wednesday
January 1, 870
- Ended on
-
Wednesday
December 31, 870
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
870s
870–879
- Century
-
9th century
801–900
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,156
1156 years before 2026.
In other calendars
- Hebrew
-
4630 / 4631 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
256 / 257 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Tiger
Sexagenary cycle position 27 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1413 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
248 / 249 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
862 / 863 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
792 / 791 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 2 × 3 × 5 × 29
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- eight hundred seventy
- Ordinal
- 870th
- Roman numeral
- DCCCLXX
- Binary
- 1101100110
- Octal
- 1546
- Hexadecimal
- 0x366
- Base64
- A2Y=
- One's complement
- 64,665 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹𒁹𒁹𒁹 𒌋𒌋𒌋
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆
- Greek (Milesian)
- ωοʹ
- Mayan (base 20)
- 𝋢·𝋣·𝋪
- Chinese
- 八百七十
- Chinese (financial)
- 捌佰柒拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 870 = 8
- e — Euler's number (e)
- Digit 870 = 4
- φ — Golden ratio (φ)
- Digit 870 = 5
- √2 — Pythagoras's (√2)
- Digit 870 = 2
- ln 2 — Natural log of 2
- Digit 870 = 9
- γ — Euler-Mascheroni (γ)
- Digit 870 = 9
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 870, here are decompositions:
- 7 + 863 = 870
- 11 + 859 = 870
- 13 + 857 = 870
- 17 + 853 = 870
- 31 + 839 = 870
- 41 + 829 = 870
- 43 + 827 = 870
- 47 + 823 = 870
Showing the first eight; more decompositions exist.
UTF-8 encoding: CD A6 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.102.
- Address
- 0.0.3.102
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.3.102
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 870 is an active NANP area code (North American Numbering Plan).
- Primary area
- Eastern Arkansas / Jonesboro
- Region
- Arkansas
- 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.