Number

1,220

1,220 is a composite number, even, a calendar year.

1,220 (one thousand two hundred twenty) is an even 4-digit number. It is a composite number with 12 divisors, and factors as 2² × 5 × 61. Its proper divisors sum to 1,384, more than the number itself, making it an abundant number. Written other ways, in Roman numerals it is MCCXX and in binary, 10011000100.

Abundant Number Arithmetic Number Cube-Free Evil Number Gapful Number Harshad / Niven Recamán's Sequence Semiperfect Number Year

Interestingness

★ ★ ★ ★ ☆

6 notable facts · grade B

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 1,231 1,232

less more

Historical context — 1220 AD

Calendar year

Year 1220 (MCCXX) was a leap year starting on Wednesday of the Julian calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →

Year facts

Year type: Leap year
Divisible by 4 and not by 100; February has 29 days.
Days in year: 366
ISO weeks: 53
Long year: contains 53 ISO weeks.
Started on: Wednesday
January 1, 1220
Ended on: Thursday
December 31, 1220
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 1220s
1220–1229
Century: 13th century
1201–1300
Millennium: 2nd millennium
1001–2000
Years ago: 806
806 years before 2026.

In other calendars

Hebrew: 4980 / 4981 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 616 / 617 AH
Lunar calendar; year spans differ from Gregorian.
Chinese: Year of the zodiac:Metal zodiac:Dragon
Sexagenary cycle position 17 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1763 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 598 / 599 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1212 / 1213 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1142 / 1141 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 4
Digit sum: 5
Digit product: 0
Digital root: 5
Palindrome: No
Bit width: 11 bits
Reversed: 221
Recamán's sequence: a(8,548) = 1,220
Square (n²): 1,488,400
Cube (n³): 1,815,848,000
Divisor count: 12
σ(n) — sum of divisors: 2,604
φ(n) — Euler's totient: 480
Sum of prime factors: 70

Primality

Prime factorization: 2 ² × 5 × 61

Nearest primes: 1,217 (−3) · 1,223 (+3)

Divisors & multiples

All divisors (12)

1 · 2 · 4 · 5 · 10 · 20 · 61 · 122 · 244 · 305 · 610 (half) · 1220

Aliquot sum (sum of proper divisors): 1,384

Factor pairs (a × b = 1,220)

1 × 1220

2 × 610

4 × 305

5 × 244

10 × 122

20 × 61

First multiples

1,220 · 2,440 (double) · 3,660 · 4,880 · 6,100 · 7,320 · 8,540 · 9,760 · 10,980 · 12,200

Sums & aliquot sequence

As a sum of two squares: 8² + 34² = 14² + 32²

As consecutive integers: 242 + 243 + 244 + 245 + 246 149 + 150 + … + 156 11 + 12 + … + 50

Aliquot sequence: 1,220 → 1,384 → 1,226 → 616 → 824 → 736 → 776 → 694 → 350 → 394 → 200 → 265 → 59 → 1 → 0 — terminates at zero

Continued fraction of √n

√1,220 = [34; (1, 12, 1, 68)]

Period length 4 — the block in parentheses repeats forever.

Representations

In words: one thousand two hundred twenty
Ordinal: 1220th
Roman numeral: MCCXX
Binary: 10011000100
Octal: 2304
Hexadecimal: 0x4C4
Base64: BMQ=
One's complement: 64,315 (16-bit)
Scientific notation: 1.22 × 10³
As a duration: 1,220 s = 20 minutes, 20 seconds

In other bases

ternary (3) 1200012

quaternary (4) 103010

quinary (5) 14340

senary (6) 5352

septenary (7) 3362

nonary (9) 1605

undecimal (11) a0a

duodecimal (12) 858

tridecimal (13) 72b

tetradecimal (14) 632

pentadecimal (15) 565

Palindromic in base 11, base 12, base 15, base 16

As an angle

1,220° = 3 × 360° + 140°

140° ≈ 2.443 rad

Compass bearing: SE (southeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋 𒌋𒌋
Egyptian hieroglyphic: 𓆼𓍢𓍢𓎆𓎆
Greek (Milesian): ͵ασκʹ
Mayan (base 20): 𝋣·𝋡·𝋠
Chinese: 一千二百二十
Chinese (financial): 壹仟貳佰貳拾

In other modern scripts

Eastern Arabic ١٢٢٠ Devanagari १२२० Bengali ১২২০ Tamil ௧௨௨௦ Thai ๑๒๒๐ Tibetan ༡༢༢༠ Khmer ១២២០ Lao ໑໒໒໐ Burmese ၁၂၂၀

Digit at this position in famous constants

π — Pi (π): Digit 1,220 = 1
e — Euler's number (e): Digit 1,220 = 3
φ — Golden ratio (φ): Digit 1,220 = 4
√2 — Pythagoras's (√2): Digit 1,220 = 1
ln 2 — Natural log of 2: Digit 1,220 = 7
γ — Euler-Mascheroni (γ): Digit 1,220 = 0

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1220, here are decompositions:

3 + 1217 = 1220
7 + 1213 = 1220
19 + 1201 = 1220
67 + 1153 = 1220
97 + 1123 = 1220
103 + 1117 = 1220
127 + 1093 = 1220
151 + 1069 = 1220

Showing the first eight; more decompositions exist.

Unicode codepoint

Cyrillic Small Letter Ka With Hook

U+04C4

Lowercase letter (Ll)

UTF-8 encoding: D3 84 (2 bytes).

Lookup U+04C4 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0004C4

RGB(0, 4, 196)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.4.196.

Address: 0.0.4.196
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.4.196

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

Musical pitch

Heard as a frequency, 1,220 Hz is closest to:

Concert pitch (A4 = 440 Hz): D♯6 (1244.5 Hz, -34¢)
Scientific pitch (C4 = 256 Hz): D♯6 (1217.7 Hz, +3¢)
Baroque pitch (A4 = 415 Hz): E6 (1243.6 Hz, -33¢)

Position in π

The digit sequence 1220 first appears in π at position 36,497 of the decimal expansion (the 36,497ordinal-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 1220 on Pi Search ↗