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Number

1,820

1,820 is a composite number, even, a calendar year.

Abundant Number Pentagonal Year

Properties

Parity
Even
Digit count
4
Digit sum
11
Digital root
2
Palindrome
No
Divisor count
24
σ(n) — sum of divisors
4,704

Primality

Prime factorization: 2 2 × 5 × 7 × 13

Divisors & multiples

All divisors (24)
1 · 2 · 4 · 5 · 7 · 10 · 13 · 14 · 20 · 26 · 28 · 35 · 52 · 65 · 70 · 91 · 130 · 140 · 182 · 260 · 364 · 455 · 910 · 1820
Aliquot sum (sum of proper divisors): 2,884
Factor pairs (a × b = 1,820)
1 × 1820
2 × 910
4 × 455
5 × 364
7 × 260
10 × 182
13 × 140
14 × 130
20 × 91
26 × 70
28 × 65
35 × 52
First multiples
1,820 · 3,640 · 5,460 · 7,280 · 9,100 · 10,920 · 12,740 · 14,560 · 16,380 · 18,200

Representations

In words
one thousand eight hundred twenty
Ordinal
1820th
Roman numeral
MDCCCXX
Binary
11100011100
Octal
3434
Hexadecimal
71C

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1820, here are decompositions:

  • 19 + 1801 = 1820
  • 31 + 1789 = 1820
  • 37 + 1783 = 1820
  • 43 + 1777 = 1820
  • 61 + 1759 = 1820
  • 67 + 1753 = 1820
  • 73 + 1747 = 1820
  • 79 + 1741 = 1820

Showing the first eight; more decompositions exist.

Unicode codepoint
ܜ
U+071C
Other letter (Lo)

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

Lookup U+071C on Compart ↗ Lookup on FileFormat.Info ↗
Hex color
#00071C
RGB(0, 7, 28)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.7.28.