Number

1,218

1,218 is a composite number, even, a calendar year.

1,218 (one thousand two hundred eighteen) is an even 4-digit number. It is a composite number with 16 divisors, and factors as 2 × 3 × 7 × 29. Its proper divisors sum to 1,662, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is MCCXVIII and in binary, 10011000010.

Abundant Number Arithmetic Number Cube-Free Evil Number Happy Number Practical Number Recamán's Sequence Semiperfect Number Squarefree Year

Interestingness

★ ★ ★ ★ ☆

7 notable facts · grade B

1,206 1,207 1,208 1,209 1,210 1,211 1,212 1,213 1,214 1,215 1,216 1,217 1,218 1,219 1,220 1,221 1,222 1,223 1,224 1,225 1,226 1,227 1,228 1,229 1,230

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Historical context — 1218 AD

Calendar year

Year 1218 (MCCXVIII) was a common year starting on Monday of the Julian 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: Monday
January 1, 1218
Ended on: Monday
December 31, 1218
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 1210s
1210–1219
Century: 13th century
1201–1300
Millennium: 2nd millennium
1001–2000
Years ago: 808
808 years before 2026.

In other calendars

Hebrew: 4978 / 4979 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 614 / 615 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Earth zodiac:Tiger
Sexagenary cycle position 15 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1761 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 596 / 597 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1210 / 1211 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1140 / 1139 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 4
Digit sum: 12
Digit product: 16
Digital root: 3
Palindrome: No
Bit width: 11 bits
Reversed: 8,121
Recamán's sequence: a(8,552) = 1,218
Square (n²): 1,483,524
Cube (n³): 1,806,932,232
Divisor count: 16
σ(n) — sum of divisors: 2,880
φ(n) — Euler's totient: 336
Sum of prime factors: 41

Primality

Prime factorization: 2 × 3 × 7 × 29

Nearest primes: 1,217 (−1) · 1,223 (+5)

Divisors & multiples

All divisors (16)

1 · 2 · 3 · 6 · 7 · 14 · 21 · 29 · 42 · 58 · 87 · 174 · 203 · 406 · 609 (half) · 1218

Aliquot sum (sum of proper divisors): 1,662

Factor pairs (a × b = 1,218)

1 × 1218

2 × 609

3 × 406

6 × 203

7 × 174

14 × 87

21 × 58

29 × 42

First multiples

1,218 · 2,436 (double) · 3,654 · 4,872 · 6,090 · 7,308 · 8,526 · 9,744 · 10,962 · 12,180

Sums & aliquot sequence

As consecutive integers: 405 + 406 + 407 303 + 304 + 305 + 306 171 + 172 + … + 177 96 + 97 + … + 107

Aliquot sequence: 1,218 → 1,662 → 1,674 → 2,166 → 2,406 → 2,418 → 2,958 → 3,522 → 3,534 → 4,146 → 4,158 → 7,362 → 8,628 → 11,532 → 16,272 → 29,670 → 46,362 — unresolved within range

Continued fraction of √n

√1,218 = [34; (1, 8, 1, 68)]

Period length 4 — the block in parentheses repeats forever.

Representations

In words: one thousand two hundred eighteen
Ordinal: 1218th
Roman numeral: MCCXVIII
Binary: 10011000010
Octal: 2302
Hexadecimal: 0x4C2
Base64: BMI=
One's complement: 64,317 (16-bit)
Scientific notation: 1.218 × 10³
As a duration: 1,218 s = 20 minutes, 18 seconds

In other bases

ternary (3) 1200010

quaternary (4) 103002

quinary (5) 14333

senary (6) 5350

septenary (7) 3360

nonary (9) 1603

undecimal (11) a08

duodecimal (12) 856

tridecimal (13) 729

tetradecimal (14) 630

pentadecimal (15) 563

As an angle

1,218° = 3 × 360° + 138°

138° ≈ 2.409 rad

Compass bearing: SE (southeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋 𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓆼𓍢𓍢𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ͵ασιηʹ
Mayan (base 20): 𝋣·𝋠·𝋲
Chinese: 一千二百一十八
Chinese (financial): 壹仟貳佰壹拾捌

In other modern scripts

Eastern Arabic ١٢١٨ Devanagari १२१८ Bengali ১২১৮ Tamil ௧௨௧௮ Thai ๑๒๑๘ Tibetan ༡༢༡༨ Khmer ១២១៨ Lao ໑໒໑໘ Burmese ၁၂၁၈

Digit at this position in famous constants

π — Pi (π): Digit 1,218 = 6
e — Euler's number (e): Digit 1,218 = 3
φ — Golden ratio (φ): Digit 1,218 = 4
√2 — Pythagoras's (√2): Digit 1,218 = 5
ln 2 — Natural log of 2: Digit 1,218 = 2
γ — Euler-Mascheroni (γ): Digit 1,218 = 5

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1218, here are decompositions:

5 + 1213 = 1218
17 + 1201 = 1218
31 + 1187 = 1218
37 + 1181 = 1218
47 + 1171 = 1218
67 + 1151 = 1218
89 + 1129 = 1218
101 + 1117 = 1218

Showing the first eight; more decompositions exist.

Unicode codepoint

Cyrillic Small Letter Zhe With Breve

U+04C2

Lowercase letter (Ll)

UTF-8 encoding: D3 82 (2 bytes).

Lookup U+04C2 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0004C2

RGB(0, 4, 194)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.4.194.

Address: 0.0.4.194
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.4.194

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

Musical pitch

Heard as a frequency, 1,218 Hz is closest to:

Concert pitch (A4 = 440 Hz): D♯6 (1244.5 Hz, -37¢)
Scientific pitch (C4 = 256 Hz): D♯6 (1217.7 Hz, exact)
Baroque pitch (A4 = 415 Hz): E6 (1243.6 Hz, -36¢)

Position in π

The digit sequence 1218 first appears in π at position 9,166 of the decimal expansion (the 9,166ordinal-suffix:th digit after the integer 3).

Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.

Look up 1218 on Pi Search ↗