21,840
21,840 is a composite number, even.
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 15
- Digit product
- 0
- Digital root
- 6
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 4,812
- Recamán's sequence
- a(168,083) = 21,840
- Square (n²)
- 476,985,600
- Cube (n³)
- 10,417,365,504,000
- Divisor count
- 80
- σ(n) — sum of divisors
- 83,328
- φ(n) — Euler's totient
- 4,608
- Sum of prime factors
- 36
Primality
Prime factorization: 2 4 × 3 × 5 × 7 × 13
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- twenty-one thousand eight hundred forty
- Ordinal
- 21840th
- Binary
- 101010101010000
- Octal
- 52520
- Hexadecimal
- 0x5550
- Base64
- VVA=
- One's complement
- 43,695 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹𒁹 ·
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆
- Greek (Milesian)
- ͵καωμʹ
- Mayan (base 20)
- 𝋢·𝋮·𝋬·𝋠
- Chinese
- 二萬一千八百四十
- Chinese (financial)
- 貳萬壹仟捌佰肆拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,840 = 0
- e — Euler's number (e)
- Digit 21,840 = 8
- φ — Golden ratio (φ)
- Digit 21,840 = 2
- √2 — Pythagoras's (√2)
- Digit 21,840 = 2
- ln 2 — Natural log of 2
- Digit 21,840 = 8
- γ — Euler-Mascheroni (γ)
- Digit 21,840 = 2
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21840, here are decompositions:
- 19 + 21821 = 21840
- 23 + 21817 = 21840
- 37 + 21803 = 21840
- 41 + 21799 = 21840
- 53 + 21787 = 21840
- 67 + 21773 = 21840
- 73 + 21767 = 21840
- 83 + 21757 = 21840
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 95 90 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.85.80.
- Address
- 0.0.85.80
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.85.80
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21840 first appears in π at position 18,372 of the decimal expansion (the 18,372ordinal-suffix:nd 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.