21,121
21,121 is a prime, odd.
21,121 (twenty-one thousand one hundred twenty-one) is an odd 5-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in hexadecimal, 0x5281.
Interestingness
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 7
- Digit product
- 4
- Digital root
- 7
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 12,112
- Recamán's sequence
- a(41,597) = 21,121
- Square (n²)
- 446,096,641
- Cube (n³)
- 9,422,007,154,561
- Divisor count
- 2
- σ(n) — sum of divisors
- 21,122
- φ(n) — Euler's totient
- 21,120
Primality
21,121 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√21,121 = [145; (3, 41, 5, 3, 1, 5, 5, 1, 7, 2, 6, 1, 57, 3, 1, 3, 8, 26, 3, 3, 3, 3, 2, 8, …)]
Representations
- In words
- twenty-one thousand one hundred twenty-one
- Ordinal
- 21121st
- Binary
- 101001010000001
- Octal
- 51201
- Hexadecimal
- 0x5281
- Base64
- UoE=
- One's complement
- 44,414 (16-bit)
- Scientific notation
- 2.1121 × 10⁴
- As a duration
- 21,121 s = 5 hours, 52 minutes, 1 second
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓎆𓎆𓏺
- Greek (Milesian)
- ͵καρκαʹ
- Mayan (base 20)
- 𝋢·𝋬·𝋰·𝋡
- Chinese
- 二萬一千一百二十一
- Chinese (financial)
- 貳萬壹仟壹佰貳拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,121 = 7
- e — Euler's number (e)
- Digit 21,121 = 4
- φ — Golden ratio (φ)
- Digit 21,121 = 9
- √2 — Pythagoras's (√2)
- Digit 21,121 = 8
- ln 2 — Natural log of 2
- Digit 21,121 = 5
- γ — Euler-Mascheroni (γ)
- Digit 21,121 = 0
Also seen as
UTF-8 encoding: E5 8A 81 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.129.
- Address
- 0.0.82.129
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.82.129
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21121 first appears in π at position 68,809 of the decimal expansion (the 68,809ordinal-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.
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.