15990
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 32
- Divisor Sum
- 42336
- Proper Divisor Sum (Aliquot Sum)
- 26346
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3840
- Möbius Function
- -1
- Radical
- 15990
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 5
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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 53
- 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
- Number of connected graphs on n labeled nodes, each node being colored with one of 3 colors, such that no edge joins nodes of the same color.at n=5A002028
- a(n) = floor(n*(n-1)*(n-2)/4).at n=41A011886
- a(n) = n*(19*n + 1)/2.at n=41A022277
- a(n) = (d(n)-r(n))/2, where d = A026066 and r is the periodic sequence with fundamental period (1,0,0,0).at n=45A026067
- Numbers n such that x^n + x + 2 is irreducible over GF(3).at n=16A058059
- a(n) = n*(16*n^2 - 1).at n=9A069975
- a(n) = rad(n(n+1)(n+2)), where rad(m) is the largest squarefree number dividing m (see A007947).at n=38A078637
- The number of possible values of the squarefree kernel (A007947) shared by at least two solutions x to A056239(x) = n.at n=50A088318
- The Wiener index of the Dutch windmill graph D(5,n) (n>=1).at n=25A180579
- Number of 3-step one space leftwards or up, two space rightwards or down asymmetric rook's tours on an n X n board summed over all starting positions.at n=32A187298
- Numbers n such that the trinomial x^n-x-1 is irreducible over GF(3).at n=30A223938
- Number of (n+1) X 4 0..2 matrices with each 2 X 2 subblock idempotent.at n=13A224671
- a(n) = 2*binomial(9*n+6,n)/(3*n+2).at n=4A234509
- Denominator of c(n) = (n^2+n+2)/((n+1)*(n+2)*(n+3)).at n=38A241269
- Smallest Product_{i:lambda} prime(i) for any complete partition lambda of n.at n=25A259941
- Numerator of (n-1)*n*(n+1)/4.at n=40A276670
- Numbers k such that (4*10^k - 79)/3 is prime.at n=19A289752
- Matula-Goebel numbers of transitive rooted identity trees (or transitive finitary sets).at n=18A290760
- Numbers k such that k/10 + 1 is a square.at n=40A302576
- Expansion of x * (d/dx) Product_{k>=0} 1/(1 - x^(2^k)).at n=41A304909