8127
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 14080
- Proper Divisor Sum (Aliquot Sum)
- 5953
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4536
- Möbius Function
- 0
- Radical
- 903
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 189
- 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
- Number of 2n-bead balanced binary necklaces of fundamental period 2n, equivalent to reversed complement; also Dirichlet convolution of b_n=2^(n-1) with mu(n); also number of components of Mandelbrot set corresponding to Julia sets with an attractive n-cycle.at n=13A000740
- a(0) = 1, a(n) = 13*n^2 + 2 for n>0.at n=25A010004
- a(n) = floor(n*(n-1)*(n-2)/24).at n=59A011842
- Numbers k such that k divides 4^k - 1.at n=39A014945
- Numbers k such that k | 5^k + 1.at n=37A015951
- 9 times the triangular numbers A000217.at n=42A027468
- Concatenations C1 and C2 and C3 are all prime (see the comment lines).at n=5A034817
- Sums of 12 distinct powers of 2.at n=6A038463
- Numbers k that divide 5^k + 4^k.at n=28A045590
- Numbers k that divide 10^k + 8^k.at n=45A045608
- Catafusenes (see references for precise definition).at n=7A045635
- Number of primitive (aperiodic) word structures of length n which contain exactly two different symbols.at n=13A056278
- Number of primitive (aperiodic) palindromic structures of length n using a maximum of two different symbols.at n=28A056476
- Number of primitive (aperiodic) palindromic structures using exactly two different symbols.at n=28A056481
- Numbers k such that k | 6^k + 5^k + 4^k + 3^k + 2^k + 1^k.at n=40A056745
- Numerator of (prime(n)+1)*(prime(n+1)+1)/(4*(prime(n)*prime(n+1)+1)).at n=53A079081
- Triangular array related to Motzkin triangle A026300.at n=33A084536
- Numbers k such that the k-th prime is of the form 2*j^2 + 1.at n=31A090612
- Triangle read by rows: T(n,k) = number of lattice paths from (0,0) to (n,k) that do not go below the line y=0 and consist of steps U=(1,1), D=(1,-1) and three types of steps H=(1,0) (left factors of 3-Motzkin steps).at n=30A091965
- Expansion of (1-3*x+3*x^2)/(1-5*x+10*x^2-10*x^3+4*x^4).at n=13A098179