16858
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 28
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 25290
- Proper Divisor Sum (Aliquot Sum)
- 8432
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8428
- Möbius Function
- 1
- Radical
- 16858
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 159
- 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
- yes
- Odd
- no
Appears in sequences
- Number of alkyls S C_{n+4} H_{2n+4} with n carbon atoms.at n=11A000650
- Numbers k such that the continued fraction for sqrt(k) has period 71.at n=10A020410
- Number of binary rooted trees with n nodes and height exactly 11.at n=18A036600
- Polynomial extrapolation of 2, 3, 5, 7, 11.at n=21A061165
- Number of partitions of n having no parts with multiplicity 3.at n=38A118807
- This is to A139025 as A139025 to A014688, see A139025 for details.at n=28A139026
- Number of line segments connecting exactly 6 points in an n x n grid of points.at n=33A177722
- Consider a number of k digits n = d_(k)*10^(k-1) + d_(k-1)*10^(k-2) + … + d_(2)*10 + d_(1). Sequence lists the numbers n such that Sum_{i=1..k-1}{sigma(Sum_{j=1..i}{d_(j)*10^(j-1)})} = Sum_{i=1..k-1}{phi(Sum_{j=1..i}{d_(k-j+1)*10^(i-j)})} (see example below).at n=15A244068
- G.f.: exp( Sum_{n>=1} x^n/n * Sum_{d|n} 2^(d^2) * n^2/d^2 ).at n=4A262008
- Length of shortest prefix of the Kolakoski sequence K (A000002) containing all blocks of length n that appear in K.at n=39A283511
- a(n) = (5/128)*n^4*(n mod 2) + (((-5/128)*n^4*(n mod 2) - 26) mod n) + n^3 (n > 0).at n=20A294264
- Number of (binary) max-heaps on n elements from the set {0,1} containing exactly eight 0's.at n=21A326509
- The number of regions inside a nonagon formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.at n=2A332421
- Table read by antidiagonals: Place k equally spaced points on each side of a regular n-gon and join every pair of the n*(k+1) boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives the number of regions in the resulting planar graph.at n=42A367323
- Expansion of 1/( 1 - 4 * Sum_{k>=0} x^(3^k) / (1 - x^(3^k)) )^(1/2).at n=7A382368