81,000
81,000 is a composite number, even.
81,000 (eighty-one thousand) is an even 5-digit number. It is a composite number with 80 divisors, and factors as 2³ × 3⁴ × 5³. Its proper divisors sum to 202,140, more than the number itself, making it an abundant number. Written other ways, in hexadecimal, 0x13C68.
Interestingness
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 9
- Digit product
- 0
- Digital root
- 9
- Palindrome
- No
- Bit width
- 17 bits
- Reversed
- 18
- Flips to (rotate 180°)
- 18
- Recamán's sequence
- a(272,372) = 81,000
- Square (n²)
- 6,561,000,000
- Cube (n³)
- 531,441,000,000,000
- Divisor count
- 80
- σ(n) — sum of divisors
- 283,140
- φ(n) — Euler's totient
- 21,600
- Sum of prime factors
- 33
Primality
Prime factorization: 2 3 × 3 4 × 5 3
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√81,000 = [284; (1, 1, 1, 1, 7, 2, 2, 1, 1, 22, 5, 2, 3, 62, 1, 21, 1, 3, 1, 1, 1, 2, 1, 2, …)]
Period length 46 — the block in parentheses repeats forever.
Representations
- In words
- eighty-one thousand
- Ordinal
- 81000th
- Binary
- 10011110001101000
- Octal
- 236150
- Hexadecimal
- 0x13C68
- Base64
- ATxo
- One's complement
- 4,294,886,295 (32-bit)
- Scientific notation
- 8.1 × 10⁴
- As a duration
- 81,000 s = 22 hours, 30 minutes
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹 𒌋𒌋𒌋 ·
- Egyptian hieroglyphic
- 𓂍𓂍𓂍𓂍𓂍𓂍𓂍𓂍𓆼
- Greek (Milesian)
- ͵πα
- Mayan (base 20)
- 𝋪·𝋢·𝋪·𝋠
- Chinese
- 八萬一千
- Chinese (financial)
- 捌萬壹仟
Digit at this position in famous constants
- π — Pi (π)
- Digit 81,000 = 2
- e — Euler's number (e)
- Digit 81,000 = 2
- φ — Golden ratio (φ)
- Digit 81,000 = 9
- √2 — Pythagoras's (√2)
- Digit 81,000 = 5
- ln 2 — Natural log of 2
- Digit 81,000 = 0
- γ — Euler-Mascheroni (γ)
- Digit 81,000 = 0
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 81000, here are decompositions:
- 11 + 80989 = 81000
- 37 + 80963 = 81000
- 47 + 80953 = 81000
- 67 + 80933 = 81000
- 71 + 80929 = 81000
- 83 + 80917 = 81000
- 89 + 80911 = 81000
- 103 + 80897 = 81000
Showing the first eight; more decompositions exist.
UTF-8 encoding: F0 93 B1 A8 (4 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.1.60.104.
- Address
- 0.1.60.104
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.1.60.104
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 81000 first appears in π at position 52,390 of the decimal expansion (the 52,390ordinal-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°.