12987
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 21280
- Proper Divisor Sum (Aliquot Sum)
- 8293
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7776
- Möbius Function
- 0
- Radical
- 1443
- Omega Function (Ω)
- 5
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 200
- Smith Number
- no
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = n*(19*n - 1)/2.at n=37A022276
- a(n) = floor( a(n-1)/a(1) + a(n-3)/a(3) + a(n-5)/a(5) + ... ), for n >= 3 with a(1) = 1 and a(2) = 3.at n=34A022877
- Indices of square numbers which are also heptagonal.at n=4A046196
- a(n) = A047080(2*n+1, n+2).at n=8A047088
- Sequence A001033 gives the numbers n such that the sum of the squares of n consecutive odd numbers x^2 + (x+2)^2 + ... +(x+2n-2)^2 = k^2 for some integer k. For each n, this sequence gives the least value of k.at n=32A056132
- 40*n^2 + 9 is a square.at n=9A075873
- Numbers k such that phi(k) is a perfect 5th power.at n=37A078165
- L-th order palindromes with L > 2.at n=3A089381
- Triangle, read by rows, where column 0 is [1,-1,-2,-3,...,-n,...] and column k+1 is generated by the binomial transform of column k preceded by a zero (column k includes the k zeros above the main diagonal).at n=50A117334
- Rectangular array read by antidiagonals: a(n, k) is the number of ways to put k labeled objects into n labeled boxes so that there are no boxes with exactly one object (n, k >= 1).at n=63A131103
- First trisection of A028560.at n=37A147651
- Numbers n which are concatenations n=x//y such that x^2+y^3 is a multiple of n.at n=32A162464
- Numbers k which are concatenations k=x//y such that x^2 + y^2 - x*y = k.at n=25A162556
- a(n) is the smallest positive integer such that a(n)*n is an anagram of a(n)*8.at n=29A175697
- Number of free poly-IH19-tiles (holes allowed) with n cells.at n=8A197552
- The number of length n ternary sequences in which no symbol appears exactly once.at n=9A209528
- -9-Knödel numbers.at n=42A225513
- Table (read by rows) of the natural numbers (in ascending order) whose reciprocals have only periodic decimals of length k.at n=66A226477
- Number of (n+2) X (2+2) 0..2 arrays with every consecutive three elements in every row and column having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=1A253030
- T(n,k) = Number of (n+2) X (k+2) 0..2 arrays with every consecutive three elements in every row and column having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=4A253035