15565
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 20448
- Proper Divisor Sum (Aliquot Sum)
- 4883
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11280
- Möbius Function
- -1
- Radical
- 15565
- 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
- 40
- 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
- no
- Odd
- yes
Appears in sequences
- Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 21 (most significant digit on right).at n=17A029514
- Denominators of continued fraction convergents to sqrt(589).at n=8A042129
- Expansion of g.f.: (1-2*x) / ((x-1)*(4*x^2+2*x-1)).at n=9A052899
- Engel expansion of e^Pi = 23.14069... .at n=31A059196
- Total number of parts which are positive powers of 2 in all partitions of n.at n=29A073119
- a[n] =a[n-1] + 2*n*Prime[n]-n^2.at n=19A093809
- Number of partitions of n with at most 2 odd parts.at n=48A100835
- Column 2 of the array in A107735.at n=8A107733
- Array read by antidiagonals: A(n,k) = Verlinde numbers for quasiparabolic bundles (n >= 3, k >= 0).at n=57A107735
- Number of partitions of n with at most 3 odd parts.at n=48A114312
- Number of nondecreasing arrangements of n numbers in -4..4 with sum zero and sum of squares not greater than n*20/3.at n=16A183922
- Number of nondecreasing arrangements of n numbers in -4..4 with sum zero and sum of squares less than n*20/3.at n=16A183930
- Number of binary arrays indicating the locations of trailing edge maxima of a random length-n 0..1 array extended with zeros and convolved with -1,2,-1.at n=18A222036
- Number of bits necessary to represent u(n) in binary, where u is the Lucas-Lehmer sequence: u(0) = 100 (in binary); for n>0, u(n) = u(n-1)^2 - 2.at n=13A227615
- Maximal number of partitions having the same degree in the partition graph G(n) defined at A241150.at n=40A241152
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 654", based on the 5-celled von Neumann neighborhood.at n=36A273332
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = 1, a(1) = -2, a(2) = -2, a(3) = 1.at n=19A295736
- a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = -2, a(1) = 0, a(2) = 1, a(3) = 1.at n=18A295859
- Number of nX5 0..1 arrays with every element unequal to 0, 1, 2 or 5 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=8A318072
- a(n) is the smallest nonnegative integer m such that the integer part of tan(m) is equal to n.at n=48A327788