1,981
1,981 is a composite number, odd, a calendar year.
1,981 (one thousand nine hundred eighty-one) is an odd 4-digit number. It is a composite number with 4 divisors, and factors as 7 × 283. Written other ways, in Roman numerals it is MCMLXXXI and in binary, 11110111101.
Interestingness
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
Sums & aliquot sequence
Continued fraction of √n
√1,981 = [44; (1, 1, 29, 5, 1, 9, 17, 1, 2, 2, 1, 5, 4, 3, 1, 1, 1, 2, 2, 3, 7, 7, 1, 21, …)]
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)
- Scientific notation
- 1.981 × 10³
- As a duration
- 1,981 s = 33 minutes, 1 second
As an angle
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
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
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.
Heard as a frequency, 1,981 Hz is closest to:
- Concert pitch (A4 = 440 Hz): B6 (1975.5 Hz, +5¢)
- Scientific pitch (C4 = 256 Hz): B6 (1933.1 Hz, +42¢)
- Baroque pitch (A4 = 415 Hz): C7 (1974.1 Hz, +6¢)
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.
Related reading
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.