Number
21,491
21,491 is a prime, odd.
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 17
- Digit product
- 72
- Digital root
- 8
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 19,412
- Recamán's sequence
- a(40,857) = 21,491
- Square (n²)
- 461,863,081
- Cube (n³)
- 9,925,899,473,771
- Divisor count
- 2
- σ(n) — sum of divisors
- 21,492
- φ(n) — Euler's totient
- 21,490
Primality
21,491 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Aliquot sum (sum of proper divisors):
1
First multiples
21,491
·
42,982
(double)
·
64,473
·
85,964
·
107,455
·
128,946
·
150,437
·
171,928
·
193,419
·
214,910
Sums & aliquot sequence
As consecutive integers:
10,745 + 10,746
Representations
- In words
- twenty-one thousand four hundred ninety-one
- Ordinal
- 21491st
- Binary
- 101001111110011
- Octal
- 51763
- Hexadecimal
- 0x53F3
- Base64
- U/M=
- One's complement
- 44,044 (16-bit)
In other bases
ternary (3)
1002110222
quaternary (4)
11033303
quinary (5)
1141431
senary (6)
243255
septenary (7)
116441
nonary (9)
32428
undecimal (11)
15168
duodecimal (12)
1052b
tridecimal (13)
9a22
tetradecimal (14)
7b91
pentadecimal (15)
657b
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵καυϟαʹ
- Mayan (base 20)
- 𝋢·𝋭·𝋮·𝋫
- Chinese
- 二萬一千四百九十一
- Chinese (financial)
- 貳萬壹仟肆佰玖拾壹
In other modern scripts
Eastern Arabic
٢١٤٩١
Devanagari
२१४९१
Bengali
২১৪৯১
Tamil
௨௧௪௯௧
Thai
๒๑๔๙๑
Tibetan
༢༡༤༩༡
Khmer
២១៤៩១
Lao
໒໑໔໙໑
Burmese
၂၁၄၉၁
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,491 = 8
- e — Euler's number (e)
- Digit 21,491 = 9
- φ — Golden ratio (φ)
- Digit 21,491 = 2
- √2 — Pythagoras's (√2)
- Digit 21,491 = 6
- ln 2 — Natural log of 2
- Digit 21,491 = 4
- γ — Euler-Mascheroni (γ)
- Digit 21,491 = 2
Also seen as
Prime neighborhood
Unicode codepoint
右
CJK Unified Ideograph-53F3
U+53F3
Other letter (Lo)
UTF-8 encoding: E5 8F B3 (3 bytes).
Hex color
#0053F3
RGB(0, 83, 243)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.83.243.
- Address
- 0.0.83.243
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.83.243
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Position in π
The digit sequence 21491 first appears in π at position 45,316 of the decimal expansion (the 45,316ordinal-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.