16913
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18228
- Proper Divisor Sum (Aliquot Sum)
- 1315
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 15600
- Möbius Function
- 1
- Radical
- 16913
- 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
- 84
- 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
- a(n) = T(2*n, n), where T is given by A026519.at n=8A026525
- a(n) = T(n, floor(n/2)), T given by A026519.at n=16A026530
- a(n) = T(n, floor(n/2)), T given by A026536.at n=16A026547
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 20.at n=12A031698
- Numerators of continued fraction convergents to sqrt(922).at n=8A042782
- a(n) = concatenation of n^2 and n.at n=12A055436
- a(n) = 100*n^2 + n.at n=12A055438
- Total number of nodes in all trees with n nodes.at n=12A055543
- Number of collinear triples in a 3 X n rectangular grid.at n=33A057566
- Composite n such that both n and its reversal in base 10 are squarefree, none of the prime factors of n are palindromes and the prime factors of the reversal of n are the reversals of those of n.at n=7A083526
- Triangle read by rows: T(n,k) is the coefficient of t^k (k>=0) in the polynomial P[n,t] defined by P[1,t] = P[2,t] = 1, P[3,t] = 1+t, P[n,t] = P[n-1,t] + P^2[n-2,1] for n >= 4.at n=32A103525
- The i-th term of the generalized Fibonacci sequence [0,k,k,2k,3k,...] is given by the formula F(i) = round( k/sqrt(5) * phi^i ) provided i >= s(k); a(n) = smallest value of k such that s(k) = n.at n=19A111917
- a(n) = 169*n^2 + 13.at n=10A158548
- a(n) = 4*16^n + 8*4^n + 17.at n=3A225928
- a(n+5) = a(n+4)+a(n+3)+a(n+2)+a(n+1)+2*a(n) with a(0)=0, a(1)=a(2)=a(3)=a(4)=1.at n=17A226310
- Number of partitions of n with up to six distinct kinds of 1.at n=26A320693
- Expansion of 1/((1 - 2*x)*(1 + x + x^2 + x^3 + x^4)).at n=15A349842
- Squarefree integers k such that x^4 - k*y^2 = 1 has a nontrivial solution.at n=29A356496
- Numbers k such that the k-th standard ordered rooted tree is a generalized Bethe tree (counted by A003238).at n=34A358377
- a(n) = Sum_{k = 1..n} ( n/gcd(k, n) )^4.at n=7A372965