21,820
21,820 is a composite number, even.
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 13
- Digit product
- 0
- Digital root
- 4
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 2,812
- Recamán's sequence
- a(168,123) = 21,820
- Square (n²)
- 476,112,400
- Cube (n³)
- 10,388,772,568,000
- Divisor count
- 12
- σ(n) — sum of divisors
- 45,864
- φ(n) — Euler's totient
- 8,720
- Sum of prime factors
- 1,100
Primality
Prime factorization: 2 2 × 5 × 1091
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- twenty-one thousand eight hundred twenty
- Ordinal
- 21820th
- Binary
- 101010100111100
- Octal
- 52474
- Hexadecimal
- 0x553C
- Base64
- VTw=
- One's complement
- 43,715 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹 𒁹𒁹𒁹 𒌋𒌋𒌋𒌋
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆
- Greek (Milesian)
- ͵καωκʹ
- Mayan (base 20)
- 𝋢·𝋮·𝋫·𝋠
- Chinese
- 二萬一千八百二十
- Chinese (financial)
- 貳萬壹仟捌佰貳拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,820 = 1
- e — Euler's number (e)
- Digit 21,820 = 2
- φ — Golden ratio (φ)
- Digit 21,820 = 9
- √2 — Pythagoras's (√2)
- Digit 21,820 = 0
- ln 2 — Natural log of 2
- Digit 21,820 = 8
- γ — Euler-Mascheroni (γ)
- Digit 21,820 = 2
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21820, here are decompositions:
- 3 + 21817 = 21820
- 17 + 21803 = 21820
- 47 + 21773 = 21820
- 53 + 21767 = 21820
- 83 + 21737 = 21820
- 107 + 21713 = 21820
- 137 + 21683 = 21820
- 173 + 21647 = 21820
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 94 BC (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.85.60.
- Address
- 0.0.85.60
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.85.60
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21820 first appears in π at position 200,834 of the decimal expansion (the 200,834ordinal-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.