Number
1,981
1,981 is a composite number, odd, a calendar year.
Notable events — 1981 AD
- Jan 20 Iran releases 52 American hostages after 444 days, minutes after Reagan's inauguration.
- Mar 30 President Reagan is shot and wounded outside a Washington hotel.
- May 13 Pope John Paul II is shot in St. Peter's Square.
- Jul 29 Prince Charles and Lady Diana Spencer marry at St. Paul's Cathedral.
- Aug 1 MTV launches as the first 24-hour music video channel.
- Oct 6 Egyptian President Anwar Sadat is assassinated at a military parade.
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, 1981
- Ended on
-
Thursday
December 31, 1981
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Easter Sunday
-
April 19
Sunday, April 19, 1981
- Decade
-
1980s
1980–1989
- Century
-
20th century
1901–2000
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
45
45 years before 2026.
In other calendars
- Hebrew
-
5741 / 5742 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1401 / 1402 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Rooster
Sexagenary cycle position 58 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2524 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1359 / 1360 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1973 / 1974 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1903 / 1902 Saka
Indian national calendar; year starts in March.
- Japanese
-
Shōwa 56
Reign-era counting from the start of each emperor's reign.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 19
- Digit product
- 72
- Digital root
- 1
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 1,891
- Flips to (rotate 180°)
- 1,861
- Recamán's sequence
- a(3,789) = 1,981
- Square (n²)
- 3,924,361
- Cube (n³)
- 7,774,159,141
- Divisor count
- 4
- σ(n) — sum of divisors
- 2,272
- φ(n) — Euler's totient
- 1,692
- Sum of prime factors
- 290
Primality
Prime factorization: 7 × 283
Divisors & multiples
Aliquot sum (sum of proper divisors):
291
First multiples
Sums & aliquot sequence
As consecutive integers:
990 + 991
280 + 281 + … + 286
135 + 136 + … + 148
Aliquot sequence:
1,981 → 291 → 101 → 1 → 0
— terminates at zero
Representations
- In words
- one thousand nine hundred eighty-one
- Ordinal
- 1981st
- Roman numeral
- MCMLXXXI
- Binary
- 11110111101
- Octal
- 3675
- Hexadecimal
- 0x7BD
- Base64
- B70=
- One's complement
- 63,554 (16-bit)
In other bases
ternary (3)
2201101
quaternary (4)
132331
quinary (5)
30411
senary (6)
13101
septenary (7)
5530
nonary (9)
2641
undecimal (11)
1541
duodecimal (12)
1191
tridecimal (13)
b95
tetradecimal (14)
a17
pentadecimal (15)
8c1
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋𒁹𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵αϡπαʹ
- Mayan (base 20)
- 𝋤·𝋳·𝋡
- Chinese
- 一千九百八十一
- Chinese (financial)
- 壹仟玖佰捌拾壹
In other modern scripts
Eastern Arabic
١٩٨١
Devanagari
१९८१
Bengali
১৯৮১
Tamil
௧௯௮௧
Thai
๑๙๘๑
Tibetan
༡༩༨༡
Khmer
១៩៨១
Lao
໑໙໘໑
Burmese
၁၉၈၁
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,981 = 5
- e — Euler's number (e)
- Digit 1,981 = 8
- φ — Golden ratio (φ)
- Digit 1,981 = 4
- √2 — Pythagoras's (√2)
- Digit 1,981 = 4
- ln 2 — Natural log of 2
- Digit 1,981 = 2
- γ — Euler-Mascheroni (γ)
- Digit 1,981 = 9
Also seen as
Hex color
#0007BD
RGB(0, 7, 189)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.189.
- Address
- 0.0.7.189
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.7.189
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Position in π
The digit sequence 1981 first appears in π at position 15,176 of the decimal expansion (the 15,176ordinal-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.