15999
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 33
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 21336
- Proper Divisor Sum (Aliquot Sum)
- 5337
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10664
- Möbius Function
- 1
- Radical
- 15999
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 97
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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 k such that the continued fraction for sqrt(k) has period 98.at n=34A020437
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (composite numbers), t = (F(2), F(3), F(4), ...).at n=13A025103
- a(n) = smallest k such that 5k has a digit sum = n.at n=38A077492
- Expansion of (1 - x)/(1 - 2*x - 2*x^2 - x^3).at n=10A077995
- Smallest unhappy number that takes n steps to reach any of the unhappy cycle (4, 16, 37, 58, 89, 145, 42, 20) under iteration of sum of squares of digits map.at n=12A094406
- a(n) is the 2^n-th semiprime.at n=12A131867
- a(n) = 10*n^2 - 1.at n=39A158447
- a(n) = 40*n^2 - 1.at n=19A158598
- Smallest number that takes n steps to reach a cycle under iteration of sum-of-squares-of-digits map.at n=19A176762
- Antidiagonal sums of A179748.at n=25A186425
- a(n) = smallest index i such that A010062(i) >= 2^n.at n=17A229167
- Positions of 3's in A264977; positions of 6's in A277330.at n=35A277713
- Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 345", based on the 5-celled von Neumann neighborhood.at n=15A281221
- Number of n X n 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=5A302145
- Number of nX6 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=5A302148
- T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=60A302150
- Number of 6Xn 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=5A302154
- Expansion of x*(1 + 2*x*(5 - 4*x)*(1 + x^2)*(1 + x^4))/((1 - x)*(1 - 10*x^9)).at n=33A302556
- Bases in which 5 is a unique-period prime.at n=47A306074
- Expansion of Sum_{k>=0} k! * x^(k*(k+1)/2) / Product_{j=1..k} (1 - x^j)^j.at n=21A306665