Number
21,391
21,391 is a prime, odd.
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 16
- Digit product
- 54
- Digital root
- 7
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 19,312
- Recamán's sequence
- a(41,057) = 21,391
- Square (n²)
- 457,574,881
- Cube (n³)
- 9,787,984,279,471
- Divisor count
- 2
- σ(n) — sum of divisors
- 21,392
- φ(n) — Euler's totient
- 21,390
Primality
21,391 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Aliquot sum (sum of proper divisors):
1
First multiples
21,391
·
42,782
(double)
·
64,173
·
85,564
·
106,955
·
128,346
·
149,737
·
171,128
·
192,519
·
213,910
Sums & aliquot sequence
As consecutive integers:
10,695 + 10,696
Representations
- In words
- twenty-one thousand three hundred ninety-one
- Ordinal
- 21391st
- Binary
- 101001110001111
- Octal
- 51617
- Hexadecimal
- 0x538F
- Base64
- U48=
- One's complement
- 44,144 (16-bit)
In other bases
ternary (3)
1002100021
quaternary (4)
11032033
quinary (5)
1141031
senary (6)
243011
septenary (7)
116236
nonary (9)
32307
undecimal (11)
15087
duodecimal (12)
10467
tridecimal (13)
9976
tetradecimal (14)
7b1d
pentadecimal (15)
6511
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵κατϟαʹ
- Mayan (base 20)
- 𝋢·𝋭·𝋩·𝋫
- Chinese
- 二萬一千三百九十一
- Chinese (financial)
- 貳萬壹仟參佰玖拾壹
In other modern scripts
Eastern Arabic
٢١٣٩١
Devanagari
२१३९१
Bengali
২১৩৯১
Tamil
௨௧௩௯௧
Thai
๒๑๓๙๑
Tibetan
༢༡༣༩༡
Khmer
២១៣៩១
Lao
໒໑໓໙໑
Burmese
၂၁၃၉၁
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,391 = 0
- e — Euler's number (e)
- Digit 21,391 = 1
- φ — Golden ratio (φ)
- Digit 21,391 = 1
- √2 — Pythagoras's (√2)
- Digit 21,391 = 9
- ln 2 — Natural log of 2
- Digit 21,391 = 2
- γ — Euler-Mascheroni (γ)
- Digit 21,391 = 2
Also seen as
Prime neighborhood
Unicode codepoint
厏
CJK Unified Ideograph-538F
U+538F
Other letter (Lo)
UTF-8 encoding: E5 8E 8F (3 bytes).
Hex color
#00538F
RGB(0, 83, 143)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.83.143.
- Address
- 0.0.83.143
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.83.143
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Position in π
The digit sequence 21391 first appears in π at position 51,913 of the decimal expansion (the 51,913ordinal-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.