15086
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 23880
- Proper Divisor Sum (Aliquot Sum)
- 8794
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7128
- Möbius Function
- -1
- Radical
- 15086
- Omega Function (Ω)
- 3
- 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
- 115
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- yes
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = [ a(n-1)/a(1) + a(n-3)/a(3) + a(n-5)/a(5) + ... ], for n >= 3.at n=25A022859
- Numbers having four 2's in base 9.at n=25A043464
- Numbers whose base-4 representation contains exactly four 2's and three 3's.at n=24A045156
- Convolution of A000108 (Catalan numbers) with A020920.at n=4A045492
- Triangle related to A001700 and A000302 (powers of 4).at n=40A046658
- Take n points in general position in the plane; draw all the (infinite) straight lines joining them; sequence gives number of connected regions formed.at n=20A055503
- n satisfying sigma(n+1) = sigma(n-1).at n=22A055574
- Numbers k > 1 such that, in base 5, k and k^2 contain the same digits in the same proportion.at n=8A061659
- Numbers k such that sigma(k-1) divides sigma(k+1).at n=26A067130
- a(n) = K_4(n) = Sum_{k>=0} A090285(4,k)*2^k*binomial(n,k). a(n) = 2*(n^4+14*n^3+62*n^2+91*n+21)/3.at n=9A090296
- a(n) = (3+n)*(2 + 33*n + n^2)/6.at n=35A101860
- Numbers with no 1's in base 3 & 4 expansions.at n=45A117496
- Numbers n such that sigma(n+1) - sigma(n-1) = k*n for some integer k, where sigma(n) = A000203 (sum of divisors of n).at n=23A223137
- Numbers k such that sigma(k+1) divides sigma(k-1).at n=23A227304
- Sphenic numbers (A007304) whose neighbors are sphenic.at n=35A248202
- Indices of squares of primes in A098550.at n=31A251240
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 173", based on the 5-celled von Neumann neighborhood.at n=27A270467
- Numbers k whose nearest neighbors have the same number of divisors, the same number of distinct prime factors, and the same sum of divisors.at n=8A294173
- Indices of primes followed by a gap (distance to next larger prime) of 42.at n=39A320719
- a(n) is the number of subsets of the divisors of k which sum to k+1 where k is a number all of whose prime divisors are consecutive primes starting at 2.at n=43A359753