16405
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 20952
- Proper Divisor Sum (Aliquot Sum)
- 4547
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12288
- Möbius Function
- -1
- Radical
- 16405
- 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
- Pseudoprimes to base 84.at n=39A020212
- Numbers k such that the continued fraction for sqrt(k) has period 51.at n=26A020390
- a(n) = Sum_{ k, k|n } 2^(k-1).at n=14A034729
- Sums of 4 distinct powers of 4.at n=35A038472
- Sums of 5 distinct powers of 5.at n=10A038477
- Numbers whose base-4 representation contains exactly four 0's and four 1's.at n=0A045037
- a(n) = (-1)^(n+1) * coefficient of x^n in Sum_{k>=1} x^k/(1+2*x^k).at n=14A081295
- a(n) is the smallest k such that number of non-unitary prime divisors of central binomial coefficient, A001405(k) = C(k, floor(k/2)) equals n.at n=20A081394
- Expansion of (1-x)/(1-3x+x^2+4x^3-4x^4).at n=14A117353
- A106486-encodings of combinatorial games with value 2.at n=19A125995
- Numbers n such that (product of the first n odd primes) - 2*prime(n+2) is a prime.at n=24A139463
- Numbers in A152022 which are not products of terms of A152021.at n=33A152023
- Reduced numerators of the ratios of Pi(2^(n+1))/Pi(2^(n)).at n=18A157301
- Inverse of coefficient array of orthogonal polynomials P(n,x)=x*P(n-1,x)-(2n-3)*P(n-2,x), P(0,x)=1,P(1,x)=x.at n=59A178104
- Number of 6-step S, E, and NW-moving king's tours on an n X n board summed over all starting positions.at n=13A187511
- Partial sums of A213709.at n=17A218600
- Numbers whose base-4 and base-5 representations have only 0's and 1's.at n=5A263684
- Products of three distinct tribonacci numbers > 1.at n=35A274434
- Number of connected induced (non-null) subgraphs of the friendship graph with 2n+1 nodes.at n=6A286186
- Number of nX2 0..1 arrays with every element equal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.at n=13A297937