Live analysis

21,000

21,000 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.).

21,000 (twenty-one thousand) is an even 5-digit number. It is a composite number with 64 divisors, and factors as 2³ × 3 × 5³ × 7. Its proper divisors sum to 53,880, more than the number itself, making it an abundant number. Written other ways, in hexadecimal, 0x5208.

Abundant Number Arithmetic Number Evil Number Gapful Number Harshad / Niven Octagonal Practical Number Recamán's Sequence Semiperfect Number

Interestingness

★ ★ ★ ★ ☆

7 notable facts · grade B

20,988 20,989 20,990 20,991 20,992 20,993 20,994 20,995 20,996 20,997 20,998 20,999 21,000 21,001 21,002 21,003 21,004 21,005 21,006 21,007 21,008 21,009 21,010 21,011 21,012

less more

Properties

Parity: Even
Digit count: 5
Digit sum: 3
Digit product: 0
Digital root: 3
Palindrome: No
Bit width: 15 bits
Reversed: 12
Recamán's sequence: a(41,839) = 21,000
Square (n²): 441,000,000
Cube (n³): 9,261,000,000,000
Divisor count: 64
σ(n) — sum of divisors: 74,880
φ(n) — Euler's totient: 4,800
Sum of prime factors: 31

Primality

Prime factorization: 2 ³ × 3 × 5 ³ × 7

Nearest primes: 20,983 (−17) · 21,001 (+1)

Divisors & multiples

All divisors (64)

1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 · 10 · 12 · 14 · 15 · 20 · 21 · 24 · 25 · 28 · 30 · 35 · 40 · 42 · 50 · 56 · 60 · 70 · 75 · 84 · 100 · 105 · 120 · 125 · 140 · 150 · 168 · 175 · 200 · 210 · 250 · 280 · 300 · 350 · 375 · 420 · 500 · 525 · 600 · 700 · 750 · 840 · 875 · 1000 · 1050 · 1400 · 1500 · 1750 · 2100 · 2625 · 3000 · 3500 · 4200 · 5250 · 7000 · 10500 (half) · 21000

Aliquot sum (sum of proper divisors): 53,880

Factor pairs (a × b = 21,000)

1 × 21000

2 × 10500

3 × 7000

4 × 5250

5 × 4200

6 × 3500

7 × 3000

8 × 2625

10 × 2100

12 × 1750

14 × 1500

15 × 1400

20 × 1050

21 × 1000

24 × 875

25 × 840

28 × 750

30 × 700

35 × 600

40 × 525

42 × 500

50 × 420

56 × 375

60 × 350

70 × 300

75 × 280

84 × 250

100 × 210

105 × 200

120 × 175

125 × 168

140 × 150

First multiples

21,000 · 42,000 (double) · 63,000 · 84,000 · 105,000 · 126,000 · 147,000 · 168,000 · 189,000 · 210,000

Sums & aliquot sequence

As consecutive integers: 6,999 + 7,000 + 7,001 4,198 + 4,199 + 4,200 + 4,201 + 4,202 2,997 + 2,998 + … + 3,003 1,393 + 1,394 + … + 1,407

Aliquot sequence: 21,000 → 53,880 → 108,120 → 241,800 → 591,480 → 1,430,280 → 3,413,520 → 9,121,392 → 20,055,808 → 20,313,192 → 30,469,848 → 54,409,512 → 83,340,888 → 127,869,912 → 219,423,528 → 374,848,722 → 506,762,118 — unresolved within range

Continued fraction of √n

√21,000 = [144; (1, 10, 1, 1, 2, 11, 5, 11, 2, 1, 1, 10, 1, 288)]

Period length 14 — the block in parentheses repeats forever.

Representations

In words: twenty-one thousand
Ordinal: 21000th
Binary: 101001000001000
Octal: 51010
Hexadecimal: 0x5208
Base64: Ugg=
One's complement: 44,535 (16-bit)
Scientific notation: 2.1 × 10⁴
As a duration: 21,000 s = 5 hours, 50 minutes

In other bases

ternary (3) 1001210210

quaternary (4) 11020020

quinary (5) 1133000

senary (6) 241120

septenary (7) 115140

nonary (9) 31723

undecimal (11) 14861

duodecimal (12) 101a0

tridecimal (13) 9735

tetradecimal (14) 7920

pentadecimal (15) 6350

As an angle

21,000° = 58 × 360° + 120°

120° ≈ 2.094 rad

Compass bearing: ESE (east-southeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋 ·
Egyptian hieroglyphic: 𓂍𓂍𓆼
Greek (Milesian): ͵κα
Mayan (base 20): 𝋢·𝋬·𝋪·𝋠
Chinese: 二萬一千
Chinese (financial): 貳萬壹仟

In other modern scripts

Eastern Arabic ٢١٠٠٠ Devanagari २१००० Bengali ২১০০০ Tamil ௨௧௦௦௦ Thai ๒๑๐๐๐ Tibetan ༢༡༠༠༠ Khmer ២១០០០ Lao ໒໑໐໐໐ Burmese ၂၁၀၀၀

Digit at this position in famous constants

π — Pi (π): Digit 21,000 = 1
e — Euler's number (e): Digit 21,000 = 0
φ — Golden ratio (φ): Digit 21,000 = 6
√2 — Pythagoras's (√2): Digit 21,000 = 4
ln 2 — Natural log of 2: Digit 21,000 = 0
γ — Euler-Mascheroni (γ): Digit 21,000 = 0

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21000, here are decompositions:

17 + 20983 = 21000
19 + 20981 = 21000
37 + 20963 = 21000
41 + 20959 = 21000
53 + 20947 = 21000
61 + 20939 = 21000
71 + 20929 = 21000
79 + 20921 = 21000

Showing the first eight; more decompositions exist.

Unicode codepoint

刈

CJK Unified Ideograph-5208

U+5208

Other letter (Lo)

UTF-8 encoding: E5 88 88 (3 bytes).

Lookup U+5208 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#005208

RGB(0, 82, 8)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.8.

Address: 0.0.82.8
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.82.8

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

Position in π

The digit sequence 21000 first appears in π at position 158,074 of the decimal expansion (the 158,074ordinal-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 21000 on Pi Search ↗