Number

1,818

1,818 is a composite number, even, a calendar year.

1,818 (one thousand eight hundred eighteen) is an even 4-digit number. It is a composite number with 12 divisors, and factors as 2 × 3² × 101. Its proper divisors sum to 2,160, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is MDCCCXVIII and in binary, 11100011010.

Abundant Number Cube-Free Evil Number Flippable Gapful Number Happy Number Harshad / Niven Moran Number Recamán's Sequence Self Number Semiperfect Number Undulating Number Year

Interestingness

★ ★ ★ ★ ★

10 notable facts · grade A

1,806 1,807 1,808 1,809 1,810 1,811 1,812 1,813 1,814 1,815 1,816 1,817 1,818 1,819 1,820 1,821 1,822 1,823 1,824 1,825 1,826 1,827 1,828 1,829 1,830

less more

Notable events — 1818 AD

Oct 20 The Anglo-American Convention sets the US-Canada border along the 49th parallel.
Dec 3 Illinois becomes the 21st US state.
Feb 12 Chile formally declares independence at Talca.
Mar 24 Lord Byron publishes Childe Harold's Pilgrimage Canto IV.
Jan 1 Mary Shelley anonymously publishes Frankenstein.

Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0

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, 1818
Ended on: Thursday
December 31, 1818
Friday the 13ths: 3
3 Friday the 13ths this year.
Easter Sunday: March 22
Sunday, March 22, 1818
Decade: 1810s
1810–1819
Century: 19th century
1801–1900
Millennium: 2nd millennium
1001–2000
Years ago: 208
208 years before 2026.

In other calendars

Hebrew: 5578 / 5579 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 1233 / 1234 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: 2361 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 1196 / 1197 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1810 / 1811 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1740 / 1739 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 4
Digit sum: 18
Digit product: 64
Digital root: 9
Palindrome: No
Bit width: 11 bits
Reversed: 8,181
Flips to (rotate 180°): 8,181
Recamán's sequence: a(459) = 1,818
Square (n²): 3,305,124
Cube (n³): 6,008,715,432
Divisor count: 12
σ(n) — sum of divisors: 3,978
φ(n) — Euler's totient: 600
Sum of prime factors: 109

Primality

Prime factorization: 2 × 3 ² × 101

Nearest primes: 1,811 (−7) · 1,823 (+5)

Divisors & multiples

All divisors (12)

1 · 2 · 3 · 6 · 9 · 18 · 101 · 202 · 303 · 606 · 909 (half) · 1818

Aliquot sum (sum of proper divisors): 2,160

Factor pairs (a × b = 1,818)

1 × 1818

2 × 909

3 × 606

6 × 303

9 × 202

18 × 101

First multiples

1,818 · 3,636 (double) · 5,454 · 7,272 · 9,090 · 10,908 · 12,726 · 14,544 · 16,362 · 18,180

Sums & aliquot sequence

As a sum of two squares: 27² + 33²

As consecutive integers: 605 + 606 + 607 453 + 454 + 455 + 456 198 + 199 + … + 206 146 + 147 + … + 157

Aliquot sequence: 1,818 → 2,160 → 5,280 → 12,864 → 21,680 → 28,912 → 31,848 → 47,832 → 71,808 → 148,512 → 359,520 → 946,848 → 1,895,712 → 4,539,360 → 12,180,336 → 23,781,648 → 44,267,568 — unresolved within range

Continued fraction of √n

√1,818 = [42; (1, 1, 1, 3, 4, 1, 2, 1, 8, 1, 2, 1, 4, 3, 1, 1, 1, 84)]

Period length 18 — the block in parentheses repeats forever.

Representations

In words: one thousand eight hundred eighteen
Ordinal: 1818th
Roman numeral: MDCCCXVIII
Binary: 11100011010
Octal: 3432
Hexadecimal: 0x71A
Base64: Bxo=
One's complement: 63,717 (16-bit)
Scientific notation: 1.818 × 10³
As a duration: 1,818 s = 30 minutes, 18 seconds

In other bases

ternary (3) 2111100

quaternary (4) 130122

quinary (5) 24233

senary (6) 12230

septenary (7) 5205

nonary (9) 2440

undecimal (11) 1403

duodecimal (12) 1076

tridecimal (13) a9b

tetradecimal (14) 93c

pentadecimal (15) 813

As an angle

1,818° = 5 × 360° + 18°

18° ≈ 0.314 rad

Compass bearing: NNE (north-northeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒌋 𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ͵αωιηʹ
Mayan (base 20): 𝋤·𝋪·𝋲
Chinese: 一千八百一十八
Chinese (financial): 壹仟捌佰壹拾捌

In other modern scripts

Eastern Arabic ١٨١٨ Devanagari १८१८ Bengali ১৮১৮ Tamil ௧௮௧௮ Thai ๑๘๑๘ Tibetan ༡༨༡༨ Khmer ១៨១៨ Lao ໑໘໑໘ Burmese ၁၈၁၈

Digit at this position in famous constants

π — Pi (π): Digit 1,818 = 0
e — Euler's number (e): Digit 1,818 = 2
φ — Golden ratio (φ): Digit 1,818 = 9
√2 — Pythagoras's (√2): Digit 1,818 = 3
ln 2 — Natural log of 2: Digit 1,818 = 4
γ — Euler-Mascheroni (γ): Digit 1,818 = 9

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1818, here are decompositions:

7 + 1811 = 1818
17 + 1801 = 1818
29 + 1789 = 1818
31 + 1787 = 1818
41 + 1777 = 1818
59 + 1759 = 1818
71 + 1747 = 1818
97 + 1721 = 1818

Showing the first eight; more decompositions exist.

Unicode codepoint

Syriac Letter Heth

U+071A

Other letter (Lo)

UTF-8 encoding: DC 9A (2 bytes).

Lookup U+071A on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00071A

RGB(0, 7, 26)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.26.

Address: 0.0.7.26
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.7.26

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

Musical pitch

Heard as a frequency, 1,818 Hz is closest to:

Concert pitch (A4 = 440 Hz): A♯6 (1864.7 Hz, -44¢)
Scientific pitch (C4 = 256 Hz): A♯6 (1824.6 Hz, -6¢)
Baroque pitch (A4 = 415 Hz): B6 (1863.3 Hz, -43¢)

Position in π

The digit sequence 1818 first appears in π at position 1,572 of the decimal expansion (the 1,572ordinal-suffix:nd 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 1818 on Pi Search ↗