21,018
21,018 is a composite number, even.
21,018 (twenty-one thousand eighteen) is an even 5-digit number. It is a composite number with 16 divisors, and factors as 2 × 3 × 31 × 113. Its proper divisors sum to 22,758, more than the number itself, making it an abundant number. Written other ways, in hexadecimal, 0x521A.
Interestingness
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 12
- Digit product
- 0
- Digital root
- 3
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 81,012
- Recamán's sequence
- a(41,803) = 21,018
- Square (n²)
- 441,756,324
- Cube (n³)
- 9,284,834,417,832
- Divisor count
- 16
- σ(n) — sum of divisors
- 43,776
- φ(n) — Euler's totient
- 6,720
- Sum of prime factors
- 149
Primality
Prime factorization: 2 × 3 × 31 × 113
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√21,018 = [144; (1, 40, 2, 2, 1, 5, 4, 1, 10, 2, 1, 8, 1, 2, 10, 1, 4, 5, 1, 2, 2, 40, 1, 288)]
Period length 24 — the block in parentheses repeats forever.
Representations
- In words
- twenty-one thousand eighteen
- Ordinal
- 21018th
- Binary
- 101001000011010
- Octal
- 51032
- Hexadecimal
- 0x521A
- Base64
- Uho=
- One's complement
- 44,517 (16-bit)
- Scientific notation
- 2.1018 × 10⁴
- As a duration
- 21,018 s = 5 hours, 50 minutes, 18 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋 𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵καιηʹ
- Mayan (base 20)
- 𝋢·𝋬·𝋪·𝋲
- Chinese
- 二萬一千零一十八
- Chinese (financial)
- 貳萬壹仟零壹拾捌
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,018 = 1
- e — Euler's number (e)
- Digit 21,018 = 9
- φ — Golden ratio (φ)
- Digit 21,018 = 7
- √2 — Pythagoras's (√2)
- Digit 21,018 = 4
- ln 2 — Natural log of 2
- Digit 21,018 = 2
- γ — Euler-Mascheroni (γ)
- Digit 21,018 = 1
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21018, here are decompositions:
- 5 + 21013 = 21018
- 7 + 21011 = 21018
- 17 + 21001 = 21018
- 37 + 20981 = 21018
- 59 + 20959 = 21018
- 71 + 20947 = 21018
- 79 + 20939 = 21018
- 89 + 20929 = 21018
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 88 9A (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.26.
- Address
- 0.0.82.26
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.82.26
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21018 first appears in π at position 76,385 of the decimal expansion (the 76,385ordinal-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
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.