number.wiki

Number

280

280 is a composite number, even, a calendar year.

Abundant Number Arithmetic Number Gapful Number Happy Number Harshad / Niven Octagonal Odious Number Pernicious Number Practical Number Recamán's Sequence Semiperfect Number Year

Historical context — 280 AD

Calendar year

Year 280 (CCLXXX) was a leap year starting on Thursday of the Julian calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →

Historical context — 280 BC

Calendar year

Year 280 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: Leap year
Divisible by 4 and not by 100; February has 29 days.
Days in year: 366
ISO weeks: 53
Long year: contains 53 ISO weeks.
Started on: Thursday
January 1, 280
Ended on: Friday
December 31, 280
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 280s
280–289
Century: 3rd century
201–300
Millennium: 1st millennium
1–1000
Years ago: 1,746
1746 years before 2026.

In other calendars

Hebrew: 4040 / 4041 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Metal zodiac:Rat
Sexagenary cycle position 37 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 823 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 272 / 273 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 202 / 201 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 3
Digit sum: 10
Digit product: 0
Digital root: 1
Palindrome: No
Bit width: 9 bits
Reversed: 82
Recamán's sequence: a(159) = 280
Square (n²): 78,400
Cube (n³): 21,952,000
Divisor count: 16
σ(n) — sum of divisors: 720
φ(n) — Euler's totient: 96
Sum of prime factors: 18

Primality

Prime factorization: 2 ³ × 5 × 7

Nearest primes: 277 (−3) · 281 (+1)

Divisors & multiples

All divisors (16)

1 · 2 · 4 · 5 · 7 · 8 · 10 · 14 · 20 · 28 · 35 · 40 · 56 · 70 · 140 (half) · 280

Aliquot sum (sum of proper divisors): 440

Factor pairs (a × b = 280)

1 × 280

2 × 140

4 × 70

5 × 56

7 × 40

8 × 35

10 × 28

14 × 20

First multiples

280 · 560 (double) · 840 · 1,120 · 1,400 · 1,680 · 1,960 · 2,240 · 2,520 · 2,800

Sums & aliquot sequence

As consecutive integers: 54 + 55 + 56 + 57 + 58 37 + 38 + … + 43 10 + 11 + … + 25

Aliquot sequence: 280 → 440 → 640 → 890 → 730 → 602 → 454 → 230 → 202 → 104 → 106 → 56 → 64 → 63 → 41 → 1 → 0 — terminates at zero

Representations

In words: two hundred eighty
Ordinal: 280th
Roman numeral: CCLXXX
Binary: 100011000
Octal: 430
Hexadecimal: 0x118
Base64: ARg=
One's complement: 65,255 (16-bit)

In other bases

ternary (3) 101101

quaternary (4) 10120

quinary (5) 2110

senary (6) 1144

septenary (7) 550

nonary (9) 341

undecimal (11) 235

duodecimal (12) 1b4

tridecimal (13) 187

tetradecimal (14) 160

pentadecimal (15) 13a

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋
Egyptian hieroglyphic: 𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
Greek (Milesian): σπʹ
Mayan (base 20): 𝋮·𝋠
Chinese: 二百八十
Chinese (financial): 貳佰捌拾

In other modern scripts

Eastern Arabic ٢٨٠ Devanagari २८० Bengali ২৮০ Tamil ௨௮௦ Thai ๒๘๐ Tibetan ༢༨༠ Khmer ២៨០ Lao ໒໘໐ Burmese ၂၈၀

Digit at this position in famous constants

π — Pi (π): Digit 280 = 8
e — Euler's number (e): Digit 280 = 2
φ — Golden ratio (φ): Digit 280 = 7
√2 — Pythagoras's (√2): Digit 280 = 9
ln 2 — Natural log of 2: Digit 280 = 4
γ — Euler-Mascheroni (γ): Digit 280 = 6

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 280, here are decompositions:

3 + 277 = 280
11 + 269 = 280
17 + 263 = 280
23 + 257 = 280
29 + 251 = 280
41 + 239 = 280
47 + 233 = 280
53 + 227 = 280

Showing the first eight; more decompositions exist.

Unicode codepoint

Ę

Latin Capital Letter E With Ogonek

U+0118

Uppercase letter (Lu)

UTF-8 encoding: C4 98 (2 bytes).

Lookup U+0118 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000118

RGB(0, 1, 24)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.1.24.

Address: 0.0.1.24
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.1.24

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