Number

1,980

1,980 is a composite number, even, a calendar year.

1,980 (one thousand nine hundred eighty) is an even 4-digit number. It is a composite number with 36 divisors, and factors as 2² × 3² × 5 × 11. Its proper divisors sum to 4,572, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is MCMLXXX and in binary, 11110111100.

Abundant Number Arithmetic Number Cube-Free Evil Number Flippable Gapful Number Harshad / Niven Highly Abundant Practical Number Pronic / Oblong Recamán's Sequence Refactorable Number Semiperfect Number Year

Interestingness

★ ★ ★ ★ ★

11 notable facts · grade A

1,968 1,969 1,970 1,971 1,972 1,973 1,974 1,975 1,976 1,977 1,978 1,979 1,980 1,981 1,982 1,983 1,984 1,985 1,986 1,987 1,988 1,989 1,990 1,991 1,992

less more

Notable events — 1980 AD

Feb 13 The Winter Olympics open in Lake Placid, New York.
Feb 22 The US hockey team upsets the Soviets in the "Miracle on Ice" at the Lake Placid Olympics.
May 4 Yugoslav President Josip Broz Tito dies after 35 years in power.
May 18 Mount St. Helens erupts in Washington State, killing 57.
Nov 4 Ronald Reagan defeats Jimmy Carter in the US presidential election.
Dec 8 John Lennon is shot dead outside his New York City apartment.

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

Year facts

Year type: Leap year
Divisible by 4 and not by 100; February has 29 days.
Days in year: 366
ISO weeks: 52
Started on: Tuesday
January 1, 1980
Ended on: Wednesday
December 31, 1980
Friday the 13ths: 1
One Friday the 13th this year.
Easter Sunday: April 6
Sunday, April 6, 1980
Decade: 1980s
1980–1989
Century: 20th century
1901–2000
Millennium: 2nd millennium
1001–2000
Years ago: 46
46 years before 2026.
US presidential election: Yes
US holds a presidential election in years divisible by 4 starting from 1788.
Summer Olympics: Yes
Winter Olympics: Yes
Held in the same year as the Summer Games until 1992.

In other calendars

Hebrew: 5740 / 5741 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 1400 / 1401 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Monkey
Sexagenary cycle position 57 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 2523 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 1358 / 1359 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1972 / 1973 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1902 / 1901 Saka
Indian national calendar; year starts in March.
Japanese: Shōwa 55
Reign-era counting from the start of each emperor's reign.

Properties

Parity: Even
Digit count: 4
Digit sum: 18
Digit product: 0
Digital root: 9
Palindrome: No
Bit width: 11 bits
Reversed: 891
Flips to (rotate 180°): 861
Recamán's sequence: a(3,791) = 1,980
Square (n²): 3,920,400
Cube (n³): 7,762,392,000
Divisor count: 36
σ(n) — sum of divisors: 6,552
φ(n) — Euler's totient: 480
Sum of prime factors: 26

Primality

Prime factorization: 2 ² × 3 ² × 5 × 11

Nearest primes: 1,979 (−1) · 1,987 (+7)

Divisors & multiples

All divisors (36)

1 · 2 · 3 · 4 · 5 · 6 · 9 · 10 · 11 · 12 · 15 · 18 · 20 · 22 · 30 · 33 · 36 · 44 · 45 · 55 · 60 · 66 · 90 · 99 · 110 · 132 · 165 · 180 · 198 · 220 · 330 · 396 · 495 · 660 · 990 (half) · 1980

Aliquot sum (sum of proper divisors): 4,572

Factor pairs (a × b = 1,980)

1 × 1980

2 × 990

3 × 660

4 × 495

5 × 396

6 × 330

9 × 220

10 × 198

11 × 180

12 × 165

15 × 132

18 × 110

20 × 99

22 × 90

30 × 66

33 × 60

36 × 55

44 × 45

First multiples

1,980 · 3,960 (double) · 5,940 · 7,920 · 9,900 · 11,880 · 13,860 · 15,840 · 17,820 · 19,800

Sums & aliquot sequence

As consecutive integers: 659 + 660 + 661 394 + 395 + 396 + 397 + 398 244 + 245 + … + 251 216 + 217 + … + 224

Aliquot sequence: 1,980 → 4,572 → 7,076 → 5,944 → 5,216 → 5,116 → 3,844 → 3,107 → 253 → 35 → 13 → 1 → 0 — terminates at zero

Continued fraction of √n

√1,980 = [44; (2, 88)]

Period length 2 — the block in parentheses repeats forever.

Representations

In words: one thousand nine hundred eighty
Ordinal: 1980th
Roman numeral: MCMLXXX
Binary: 11110111100
Octal: 3674
Hexadecimal: 0x7BC
Base64: B7w=
One's complement: 63,555 (16-bit)
Scientific notation: 1.98 × 10³
As a duration: 1,980 s = 33 minutes

In other bases

ternary (3) 2201100

quaternary (4) 132330

quinary (5) 30410

senary (6) 13100

septenary (7) 5526

nonary (9) 2640

undecimal (11) 1540

duodecimal (12) 1190

tridecimal (13) b94

tetradecimal (14) a16

pentadecimal (15) 8c0

As an angle

1,980° = 5 × 360° + 180°

180° ≈ 3.142 rad

Compass bearing: S (south)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒌋𒁹𒁹𒁹 ·
Egyptian hieroglyphic: 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
Greek (Milesian): ͵αϡπʹ
Mayan (base 20): 𝋤·𝋳·𝋠
Chinese: 一千九百八十
Chinese (financial): 壹仟玖佰捌拾

In other modern scripts

Eastern Arabic ١٩٨٠ Devanagari १९८० Bengali ১৯৮০ Tamil ௧௯௮௦ Thai ๑๙๘๐ Tibetan ༡༩༨༠ Khmer ១៩៨០ Lao ໑໙໘໐ Burmese ၁၉၈၀

Digit at this position in famous constants

π — Pi (π): Digit 1,980 = 4
e — Euler's number (e): Digit 1,980 = 1
φ — Golden ratio (φ): Digit 1,980 = 3
√2 — Pythagoras's (√2): Digit 1,980 = 6
ln 2 — Natural log of 2: Digit 1,980 = 7
γ — Euler-Mascheroni (γ): Digit 1,980 = 9

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1980, here are decompositions:

7 + 1973 = 1980
29 + 1951 = 1980
31 + 1949 = 1980
47 + 1933 = 1980
67 + 1913 = 1980
73 + 1907 = 1980
79 + 1901 = 1980
101 + 1879 = 1980

Showing the first eight; more decompositions exist.

Hex color

#0007BC

RGB(0, 7, 188)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.188.

Address: 0.0.7.188
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.7.188

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

Musical pitch

Heard as a frequency, 1,980 Hz is closest to:

Concert pitch (A4 = 440 Hz): B6 (1975.5 Hz, +4¢)
Scientific pitch (C4 = 256 Hz): B6 (1933.1 Hz, +42¢)
Baroque pitch (A4 = 415 Hz): C7 (1974.1 Hz, +5¢)

Position in π

The digit sequence 1980 first appears in π at position 6,633 of the decimal expansion (the 6,633ordinal-suffix:rd 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 1980 on Pi Search ↗