21,664
21,664 is a composite number, even.
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 19
- Digit product
- 288
- Digital root
- 1
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 46,612
- Recamán's sequence
- a(40,511) = 21,664
- Square (n²)
- 469,328,896
- Cube (n³)
- 10,167,541,202,944
- Divisor count
- 12
- σ(n) — sum of divisors
- 42,714
- φ(n) — Euler's totient
- 10,816
- Sum of prime factors
- 687
Primality
Prime factorization: 2 5 × 677
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- twenty-one thousand six hundred sixty-four
- Ordinal
- 21664th
- Binary
- 101010010100000
- Octal
- 52240
- Hexadecimal
- 0x54A0
- Base64
- VKA=
- One's complement
- 43,871 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹𒁹 𒁹 𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵καχξδʹ
- Mayan (base 20)
- 𝋢·𝋮·𝋣·𝋤
- Chinese
- 二萬一千六百六十四
- Chinese (financial)
- 貳萬壹仟陸佰陸拾肆
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,664 = 7
- e — Euler's number (e)
- Digit 21,664 = 0
- φ — Golden ratio (φ)
- Digit 21,664 = 3
- √2 — Pythagoras's (√2)
- Digit 21,664 = 9
- ln 2 — Natural log of 2
- Digit 21,664 = 5
- γ — Euler-Mascheroni (γ)
- Digit 21,664 = 9
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21664, here are decompositions:
- 3 + 21661 = 21664
- 17 + 21647 = 21664
- 47 + 21617 = 21664
- 53 + 21611 = 21664
- 101 + 21563 = 21664
- 107 + 21557 = 21664
- 173 + 21491 = 21664
- 197 + 21467 = 21664
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 92 A0 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.84.160.
- Address
- 0.0.84.160
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.84.160
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21664 first appears in π at position 13,940 of the decimal expansion (the 13,940ordinal-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.