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21,824

21,824 is a composite number, even.

This number doesn't have a permanent NumberWiki page yet — what you see below is computed live. Pages get added to the permanent index when they're notable (years, primes, curated, etc.).
Abundant Number Odious Number Pernicious Number Practical Number Recamán's Sequence Semiperfect Number

Properties

Parity
Even
Digit count
5
Digit sum
17
Digit product
128
Digital root
8
Palindrome
No
Bit width
15 bits
Reversed
42,812
Recamán's sequence
a(168,115) = 21,824
Square (n²)
476,286,976
Cube (n³)
10,394,486,964,224
Divisor count
28
σ(n) — sum of divisors
48,768
φ(n) — Euler's totient
9,600
Sum of prime factors
54

Primality

Prime factorization: 2 6 × 11 × 31

Nearest primes: 21,821 (−3) · 21,839 (+15)

Divisors & multiples

All divisors (28)
1 · 2 · 4 · 8 · 11 · 16 · 22 · 31 · 32 · 44 · 62 · 64 · 88 · 124 · 176 · 248 · 341 · 352 · 496 · 682 · 704 · 992 · 1364 · 1984 · 2728 · 5456 · 10912 (half) · 21824
Aliquot sum (sum of proper divisors): 26,944
Factor pairs (a × b = 21,824)
1 × 21824
2 × 10912
4 × 5456
8 × 2728
11 × 1984
16 × 1364
22 × 992
31 × 704
32 × 682
44 × 496
62 × 352
64 × 341
88 × 248
124 × 176
First multiples
21,824 · 43,648 (double) · 65,472 · 87,296 · 109,120 · 130,944 · 152,768 · 174,592 · 196,416 · 218,240

Sums & aliquot sequence

As consecutive integers: 1,979 + 1,980 + … + 1,989 689 + 690 + … + 719 107 + 108 + … + 234
Aliquot sequence: 21,824 26,944 26,650 28,034 14,734 7,946 4,474 2,240 3,856 3,646 1,826 1,198 602 454 230 202 104 — unresolved within range

Representations

In words
twenty-one thousand eight hundred twenty-four
Ordinal
21824th
Binary
101010101000000
Octal
52500
Hexadecimal
0x5540
Base64
VUA=
One's complement
43,711 (16-bit)
In other bases
ternary (3) 1002221022
quaternary (4) 11111000
quinary (5) 1144244
senary (6) 245012
septenary (7) 120425
nonary (9) 32838
undecimal (11) 15440
duodecimal (12) 10768
tridecimal (13) 9c1a
tetradecimal (14) 7d4c
pentadecimal (15) 66ee

Historical numeral systems

Babylonian (base 60)
𒁹𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹
Egyptian hieroglyphic
𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺𓏺𓏺𓏺
Greek (Milesian)
͵καωκδʹ
Mayan (base 20)
𝋢·𝋮·𝋫·𝋤
Chinese
二萬一千八百二十四
Chinese (financial)
貳萬壹仟捌佰貳拾肆
In other modern scripts
Eastern Arabic ٢١٨٢٤ Devanagari २१८२४ Bengali ২১৮২৪ Tamil ௨௧௮௨௪ Thai ๒๑๘๒๔ Tibetan ༢༡༨༢༤ Khmer ២១៨២៤ Lao ໒໑໘໒໔ Burmese ၂၁၈၂၄

Digit at this position in famous constants

π — Pi (π)
Digit 21,824 = 8
e — Euler's number (e)
Digit 21,824 = 7
φ — Golden ratio (φ)
Digit 21,824 = 1
√2 — Pythagoras's (√2)
Digit 21,824 = 0
ln 2 — Natural log of 2
Digit 21,824 = 5
γ — Euler-Mascheroni (γ)
Digit 21,824 = 1

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21824, here are decompositions:

  • 3 + 21821 = 21824
  • 7 + 21817 = 21824
  • 37 + 21787 = 21824
  • 67 + 21757 = 21824
  • 73 + 21751 = 21824
  • 97 + 21727 = 21824
  • 151 + 21673 = 21824
  • 163 + 21661 = 21824

Showing the first eight; more decompositions exist.

Unicode codepoint
CJK Unified Ideograph-5540
U+5540
Other letter (Lo)

UTF-8 encoding: E5 95 80 (3 bytes).

Hex color
#005540
RGB(0, 85, 64)
IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.85.64.

Address
0.0.85.64
Class
reserved
IPv4-mapped IPv6
::ffff:0.0.85.64

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

Position in π

The digit sequence 21824 first appears in π at position 30,153 of the decimal expansion (the 30,153ordinal-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.