8128
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 14
- Divisor Sum
- 16256
- Proper Divisor Sum (Aliquot Sum)
- 8128
- Abundant Number
- no
- Perfect Number
- yes
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4032
- Möbius Function
- 0
- Radical
- 254
- Omega Function (Ω)
- 7
- 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
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 52
- 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
- Harmonic or Ore numbers: numbers k such that the harmonic mean of the divisors of k is an integer.at n=10A001599
- a(n) = n^2*(2*n^2 - 1); also Sum_{k=0..n-1} (2k+1)^3.at n=8A002593
- a(n) = 2^(n-1)*( 2^n + (-1)^n ).at n=7A003665
- a(n) = 2^(n-1)*(2^n - 1), n >= 0.at n=7A006516
- Dual pairs of integrals arising from reflection coefficients.at n=14A007179
- Multiply-perfect numbers: n divides sigma(n).at n=6A007691
- a(n) = 2*n*(4*n - 1).at n=32A014635
- a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 6.at n=16A022320
- Expansion of 1/Product_{m>=1} (1 - m*q^m)^32.at n=3A022756
- [ (4th elementary symmetric function of S(n))/(2nd elementary symmetric function of S(n)) ], where S(n) = {first n+3 positive integers congruent to 2 mod 3}.at n=12A024402
- Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=11A027598
- Expansion of (theta_3(z)*theta_3(19z) + theta_2(z)*theta_2(19z))^4.at n=22A028644
- Numbers with 14 divisors.at n=33A030632
- Number of reversible strings with n beads of 2 colors. If more than 1 bead, not palindromic.at n=13A032085
- Hyperperfect numbers: x such that x = 1 + k*(sigma(x)-x-1) for some k > 0.at n=12A034897
- Triangular numbers (A000217) with prime indices.at n=30A034953
- Even triangular numbers with prime indices.at n=15A034955
- Harmonic seed numbers.at n=8A035527
- Sum of every 4th entry of row n in Pascal's triangle, starting at "n choose 1".at n=15A038504
- Sum of every 4th entry of row n in Pascal's triangle, starting at binomial(n,2).at n=15A038505