Number
21,001
21,001 is a prime, odd.
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 4
- Digit product
- 0
- Digital root
- 4
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 10,012
- Recamán's sequence
- a(41,837) = 21,001
- Square (n²)
- 441,042,001
- Cube (n³)
- 9,262,323,063,001
- Divisor count
- 2
- σ(n) — sum of divisors
- 21,002
- φ(n) — Euler's totient
- 21,000
Primality
21,001 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Aliquot sum (sum of proper divisors):
1
First multiples
21,001
·
42,002
(double)
·
63,003
·
84,004
·
105,005
·
126,006
·
147,007
·
168,008
·
189,009
·
210,010
Sums & aliquot sequence
As a sum of two squares:
75² + 124²
As consecutive integers:
10,500 + 10,501
Representations
- In words
- twenty-one thousand one
- Ordinal
- 21001st
- Binary
- 101001000001001
- Octal
- 51011
- Hexadecimal
- 0x5209
- Base64
- Ugk=
- One's complement
- 44,534 (16-bit)
In other bases
ternary (3)
1001210211
quaternary (4)
11020021
quinary (5)
1133001
senary (6)
241121
septenary (7)
115141
nonary (9)
31724
undecimal (11)
14862
duodecimal (12)
101a1
tridecimal (13)
9736
tetradecimal (14)
7921
pentadecimal (15)
6351
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋 𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓏺
- Greek (Milesian)
- ͵κααʹ
- Mayan (base 20)
- 𝋢·𝋬·𝋪·𝋡
- Chinese
- 二萬一千零一
- Chinese (financial)
- 貳萬壹仟零壹
In other modern scripts
Eastern Arabic
٢١٠٠١
Devanagari
२१००१
Bengali
২১০০১
Tamil
௨௧௦௦௧
Thai
๒๑๐๐๑
Tibetan
༢༡༠༠༡
Khmer
២១០០១
Lao
໒໑໐໐໑
Burmese
၂၁၀၀၁
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,001 = 2
- e — Euler's number (e)
- Digit 21,001 = 4
- φ — Golden ratio (φ)
- Digit 21,001 = 2
- √2 — Pythagoras's (√2)
- Digit 21,001 = 8
- ln 2 — Natural log of 2
- Digit 21,001 = 3
- γ — Euler-Mascheroni (γ)
- Digit 21,001 = 2
Also seen as
Unicode codepoint
刉
CJK Unified Ideograph-5209
U+5209
Other letter (Lo)
UTF-8 encoding: E5 88 89 (3 bytes).
Hex color
#005209
RGB(0, 82, 9)
IPv4 address
As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.9.
- Address
- 0.0.82.9
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.82.9
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Position in π
The digit sequence 21001 first appears in π at position 49,228 of the decimal expansion (the 49,228ordinal-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.