Number

243

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

243 (two hundred forty-three) is an odd 3-digit number. It is a composite number with 6 divisors, and factors as 3⁵. Written other ways, in Roman numerals it is CCXLIII and in binary, 11110011.

Deficient Number Evil Number Frugal Number Harshad / Niven Powerful Number Recamán's Sequence Year

Interestingness

★ ★ ☆ ☆ ☆

4 notable facts · grade D

231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255

less more

Historical context — 243 AD

Calendar year

Year 243 (CCXLIII) 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 →

Historical context — 243 BC

Calendar year

Year 243 BC was a year of the pre-Julian Roman calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 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: Sunday
January 1, 243
Ended on: Sunday
December 31, 243
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 240s
240–249
Century: 3rd century
201–300
Millennium: 1st millennium
1–1000
Years ago: 1,783
1783 years before 2026.

In other calendars

Hebrew: 4003 / 4004 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Water zodiac:Pig
Sexagenary cycle position 60 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 786 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 235 / 236 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 165 / 164 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 9
Digit product: 24
Digital root: 9
Palindrome: No
Bit width: 8 bits
Reversed: 342
Recamán's sequence: a(257) = 243
Square (n²): 59,049
Cube (n³): 14,348,907
Divisor count: 6
σ(n) — sum of divisors: 364
φ(n) — Euler's totient: 162
Sum of prime factors: 15

Primality

Prime factorization: 3 ⁵

Nearest primes: 241 (−2) · 251 (+8)

Divisors & multiples

All divisors (6)

1 · 3 · 9 · 27 · 81 · 243

Aliquot sum (sum of proper divisors): 121

Factor pairs (a × b = 243)

1 × 243

3 × 81

9 × 27

First multiples

243 · 486 (double) · 729 · 972 · 1,215 · 1,458 · 1,701 · 1,944 · 2,187 · 2,430

Sums & aliquot sequence

As a sum of two cubes: 3³ + 6³

As consecutive integers: 121 + 122 80 + 81 + 82 38 + 39 + 40 + 41 + 42 + 43 23 + 24 + … + 31

Aliquot sequence: 243 → 121 → 12 → 16 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Continued fraction of √n

√243 = [15; (1, 1, 2, 3, 15, 3, 2, 1, 1, 30)]

Period length 10 — the block in parentheses repeats forever.

Representations

In words: two hundred forty-three
Ordinal: 243rd
Roman numeral: CCXLIII
Binary: 11110011
Octal: 363
Hexadecimal: 0xF3
Base64: 8w==
One's complement: 12 (8-bit)
Scientific notation: 2.43 × 10²
As a duration: 243 s = 4 minutes, 3 seconds

In other bases

ternary (3) 100000

quaternary (4) 3303

quinary (5) 1433

senary (6) 1043

septenary (7) 465

nonary (9) 300

undecimal (11) 201

duodecimal (12) 183

tridecimal (13) 159

tetradecimal (14) 135

pentadecimal (15) 113

Palindromic in base 8

As an angle

243°

243° ≈ 4.241 rad

Compass bearing: WSW (west-southwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹 𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓍢𓎆𓎆𓎆𓎆𓏺𓏺𓏺
Greek (Milesian): σμγʹ
Mayan (base 20): 𝋬·𝋣
Chinese: 二百四十三
Chinese (financial): 貳佰肆拾參

In other modern scripts

Eastern Arabic ٢٤٣ Devanagari २४३ Bengali ২৪৩ Tamil ௨௪௩ Thai ๒๔๓ Tibetan ༢༤༣ Khmer ២៤៣ Lao ໒໔໓ Burmese ၂၄၃

Digit at this position in famous constants

π — Pi (π): Digit 243 = 7
e — Euler's number (e): Digit 243 = 6
φ — Golden ratio (φ): Digit 243 = 4
√2 — Pythagoras's (√2): Digit 243 = 4
ln 2 — Natural log of 2: Digit 243 = 2
γ — Euler-Mascheroni (γ): Digit 243 = 9

Also seen as

Unicode codepoint

Latin Small Letter O With Acute

U+00F3

Lowercase letter (Ll)

UTF-8 encoding: C3 B3 (2 bytes).

Lookup U+00F3 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0000F3

RGB(0, 0, 243)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.243.

Address: 0.0.0.243
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.243

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

Musical pitch

Heard as a frequency, 243 Hz is closest to:

Concert pitch (A4 = 440 Hz): B3 (246.9 Hz, -28¢)
Scientific pitch (C4 = 256 Hz): B3 (241.6 Hz, +10¢)
Baroque pitch (A4 = 415 Hz): C4 (246.8 Hz, -27¢)