16940
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
- 1
Divisibility
- Divisor Count
- 36
- Divisor Sum
- 44688
- Proper Divisor Sum (Aliquot Sum)
- 27748
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5280
- Möbius Function
- 0
- Radical
- 770
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 58
- Smith Number
- yes
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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 discordant permutations.at n=7A000562
- a(n) = (2*n - 9)*n^2.at n=22A015243
- Numbers k whose decimal representation, read as a base-21 value and divided by k, yields an integer.at n=28A032573
- Number of nonempty subsets of {1,2,...,n} in which exactly 3/5 of the elements are <= n/3.at n=22A047200
- Number of nonempty subsets of {1,2,...,n} in which exactly 3/5 of the elements are <= (n-1)/3.at n=22A048012
- Number of nonempty subsets of {1,2,...,n} in which exactly 3/5 of the elements are <= (n-2)/3.at n=22A048023
- a(n) = (n+1)*(n+2)*(n+3)*(9n+4)/24.at n=13A051798
- Ninth convolution of A002605(n) (generalized (2,2)-Fibonacci), n>=0, with itself.at n=4A073398
- Numbers n such that sopf(sigma(n)) = sigma(sopf(n)), where sopf(x) = sum of the distinct prime factors of x.at n=30A076532
- a(1) = 1; a(n) = Sum_{k=1..n-1} phi(a(k)*a(n-k)), where phi(m) is the totient function.at n=15A105075
- Sum of numbers under a triangle on a spiral staircase of width 10.at n=19A111080
- Eleven times hexagonal numbers: a(n) = 11*n*(2*n-1).at n=28A154617
- Number of nonoverlapping placements of one 1 X 1 square and one 2 X 2 square on an n X n board.at n=11A173963
- a(n) = sigma(n*a(n-1)) for n>1 with a(1)=1.at n=5A180709
- Nonnegative values x of solutions (x, y) to the Diophantine equation x^2 + (x+84847)^2 = y^2.at n=11A201917
- a(n) = Sum_{i=0..n} digsum_5(i)^4, where digsum_5(i) = A053824(i).at n=24A231671
- a(n) = Sum_{i=0..n} digsum_6(i)^4, where digsum_6(i) = A053827(i).at n=24A231675
- Triangle read by rows: T(n,k) = number of configurations of k nonattacking bishops on the black squares of an n X n chessboard (0 <= k <= n - [n>1]).at n=60A274105
- a(n) = 2*n*(7*n - 3).at n=35A316466
- Numbers k such that the k-th composition in standard order is a permutation (of an initial interval).at n=37A333218