8091
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 12480
- Proper Divisor Sum (Aliquot Sum)
- 4389
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5040
- Möbius Function
- 0
- Radical
- 2697
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 3
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 189
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- A Fielder sequence: a(n) = a(n-1) + a(n-2) + a(n-4).at n=15A001641
- a(n) = dot_product(1,2,...,n)*(7,8,...,n,1,2,3,4,5,6).at n=24A026049
- (s(n)+2)/10, where s(n)=n-th base 10 palindrome that starts with 8.at n=31A043087
- Number of triangle-free planar graphs with n nodes.at n=9A049367
- Numbers n such that 25*2^n-1 is prime.at n=26A050538
- a(n) = ceiling(a(n-1)*3/2) with a(1) = 1.at n=21A061419
- Heights of peaks of more than 8000 meters (as of Sep 25 2001), in decreasing order.at n=9A064296
- Numbers k such that the sum of the reverses of 1,2,...,k is a perfect square.at n=6A074238
- a(n) = n*(n+2)*(n-2)/3.at n=27A077415
- Number of numbers whose base-3/2 expansion (see A024629) has n digits.at n=21A081848
- Pseudo-random numbers: Davenport's generator for 32-bit integers.at n=23A084277
- Rearrangement of positive integers so that the successive ratios (of the larger to the smaller term) are all distinct integers. a(m)/a(m-1) = a(k)/a(k-1) iff m = k (assuming a(m) > a(m-1), otherwise the ratio a(m-1)/a(m) is to be considered). Priority is given to smallest number not included earlier rather than to the successive ratio that has not occurred earlier.at n=39A084337
- (Sum of composites among next n numbers)-(sum of primes among next n numbers).at n=29A094338
- Number of A095748-primes in range ]2^n,2^(n+1)].at n=25A095758
- Least area/6 of primitive Pythagorean triangles with even leg 4n.at n=28A096898
- Numbers which are the sum of three positive cubes and divisible by 31.at n=36A104054
- a(1) = 1; for n > 1: if n is even, a(n) = least k > 0 such that sum(i=1,n/2,a(2*i-1))/sum(j=1,n,a(j))>=1/4, or 1 if there is no such k; if n is odd, a(n) = largest k > 0 such that sum(i=1,(n+1)/2,a(2*i-1))/sum(j=1,n,a(j))<=1/3, or 1 if there is no such k.at n=45A104740
- Triangle read by rows, where t(n,1) = 1, t(n,m) = t(n,m-1) + (largest nonprime {1 or composite} in row {n-1}).at n=41A120853
- First trisection of A028560.at n=29A147651
- Values of register b when register a becomes 0 for the two register machine {i[1], i[1], i[1], d[2,1], d[1,6], i[2], d[1,5], d[2,3]}.at n=21A156623