12780
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 36
- Divisor Sum
- 39312
- Proper Divisor Sum (Aliquot Sum)
- 26532
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3360
- Möbius Function
- 0
- Radical
- 2130
- 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
- 76
- 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
- yes
- Odd
- no
Appears in sequences
- Number of labeled dyslexic planted planar trees with n+1 nodes.at n=5A038035
- a(n) = Sum_{i=0..floor(n/2)} T(2i,n-2i), array T as in A049735.at n=22A049738
- Square array T(k,n) by antidiagonals, where T(k,n) is number of ways of placing n identifiable nonnegative intervals with a total of exactly k starting and/or finishing points.at n=49A059515
- Numbers k such that F(2*k + 1) is prime where F(m) is a Fibonacci number.at n=26A117517
- Numbers k such that k*(k+1)-1 and k*(k+1)+1 are twin primes and k*(k+3)-1 and k*(k+3)+1 are also twin primes.at n=11A138303
- 5 times hexagonal numbers: 5*n*(2*n-1).at n=36A152745
- a(n) = (sum of first n primes) * n.at n=19A167214
- a(n) = n*(4*n^2 - 3*n + 5)/6.at n=26A174723
- Numbers k such that 9k+4 are terms in A072841.at n=32A175518
- Number of (n+2)X3 0..2 arrays with no 2X2 subblock sum equal to any diagonal or antidiagonal neighbor 2X2 subblock sum.at n=0A187597
- T(n,k)=Number of (n+2)X(k+2) 0..2 arrays with no 2X2 subblock sum equal to any diagonal or antidiagonal neighbor 2X2 subblock sum.at n=0A187600
- Generating primitive Pythagorean triangles by using (n, n+1) gives perimeters for each n. This sequence lists the sum of these perimeters for each n triangles.at n=19A193068
- 1/3 the number of n X n 0..2 symmetric matrices with every element equal to zero, one or two horizontal and vertical neighbors.at n=3A211039
- a(n) = smallest k such that prime(n) is the n-th largest divisor of k.at n=19A226326
- a(n) is a refactorable number and the sum of all refactorable numbers <= a(n) is also a refactorable number.at n=27A235177
- Number of non-equivalent (mod D_3) ways to choose three points in an n X n X n triangular grid so that they do not form a 2 X 2 X 2 subtriangle.at n=10A237530
- Number of partitions of n such that (number of distinct parts) = maximal multiplicity of the parts.at n=47A239964
- Number of arrangements on a line of n finite closed intervals (possibly of zero length) with k distinct endpoints (n >= 1, 1 <= k <= 2*n).at n=16A300729
- G.f. A(x) satisfies: A(x) = x + x^2 / exp(A(x) - A(x^2)/2 + A(x^3)/3 - A(x^4)/4 + ...).at n=28A345233
- Number of rucksack compositions of n: every distinct partial run has a different sum.at n=17A354580