12951
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
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 18720
- Proper Divisor Sum (Aliquot Sum)
- 5769
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8628
- Möbius Function
- 0
- Radical
- 4317
- Omega Function (Ω)
- 3
- 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
- 50
- 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
- Maximal number of regions obtained by joining n points around a circle by straight lines. Also number of regions in 4-space formed by n-1 hyperplanes.at n=24A000127
- Place n equally-spaced points around a circle and join every pair of points by a chord; this divides the circle into a(n) regions.at n=24A006533
- Number of n X n matrices with nonnegative integer entries and every row and column sum <= 2.at n=4A049088
- Numbers n such that 9*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=14A103109
- Triangle read by rows: T(n,k) is number of (n-k) X k matrices, k=0..n, with nonnegative integer entries and every row and column sum <= 2.at n=40A131235
- Triangle read by rows: first define the Narayana numbers: Y(n,m)=Binomial[n, m]*Binomial[n + 1, m + 1]/(n - m + 1); then t(n,m)=Sum[(-1)^j *Y(n + 1, j)*(k + 1 - j)^n, {j, 0, k + 1}].at n=19A155796
- Expansion of g.f. (1+z)^(24)/(1-z).at n=4A171445
- Triangle, read by rows, T(n, k) = Sum_{j=0..k} (-1)^j*(k-j+1)^n*binomial(n+1, j) *binomial(n+2, j)/(j+1).at n=25A176124
- Number of n X n 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=4A300532
- Number of nX5 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=4A300536
- T(n,k)=Number of nXk 0..1 arrays with every element equal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.at n=40A300539
- Total number of binary digits in all partitions of n into distinct parts.at n=37A319140