16778
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 29
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 25170
- Proper Divisor Sum (Aliquot Sum)
- 8392
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8388
- Möbius Function
- 1
- Radical
- 16778
- 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
- 66
- 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
- a(n) = T(n,n), T given by A026519. Also a(n) = number of integer strings s(0), ..., s(n), counted by T, such that s(n) = 0.at n=13A026520
- a(n) = T(n,n), T given by A026552. Also a(n) is the number of integer strings s(0),...,s(n) counted by T, such that s(n)=0.at n=13A026553
- Binomial transform of [ 1, 0, 1, 1, 3, 6, 15, 36, 91, 231, 595, ... ], which is essentially binomial(Fibonacci(k) + 1, 2).at n=10A033191
- Decimal part of cube root of a(n) starts with 6: first term of runs.at n=23A034132
- Numbers whose base-7 representation contains exactly four 6's.at n=20A043420
- Numbers k such that 27*2^k-1 is prime.at n=34A050539
- Triangle read by rows of number of Catalan paths (nonnegative, starting and ending at 0, step +/-1) of 2n steps with all values less than or equal to k.at n=52A080935
- Number of disconnected 2-regular graphs on n vertices.at n=55A165652
- a(n) is the number of permutations of length n that avoid the pattern 321 and the mesh pattern (12, 283) or the same sequence for the mesh pattern (12, 433).at n=10A289614
- Irregular triangle read by rows: T(n,m) = number of lattice paths of type B^H terminating at point (n, m).at n=42A291085
- a(n) = A026520(2n+1).at n=6A291089
- Number of pairs (lambda,mu) of partitions lambda of n and mu of three with mu <= lambda (by diagram containment).at n=27A303853
- a(n) is the largest number that can be expressed as the sum of three positive triangular numbers in exactly n ways.at n=14A330811