12842
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 19266
- Proper Divisor Sum (Aliquot Sum)
- 6424
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6420
- Möbius Function
- 1
- Radical
- 12842
- Omega Function (Ω)
- 2
- 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
- 24
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- 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
- Dodecahedral surface numbers: a(0)=0, a(1)=1, a(2)=20, thereafter 2*((3*n-7)^2 + 21).at n=29A007589
- Sequence arising from analysis of Levine's sequence A011784: essentially a duplicate of A144005.at n=7A014623
- Numbers k such that the continued fraction for sqrt(k) has period 33.at n=35A020372
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 7.at n=36A031420
- Becomes prime after exactly 7 iterations of f(x) = sum of prime factors of x.at n=28A047826
- Numbers n such that 155*2^n-1 is prime.at n=19A050619
- Nearest integer to 1/sum(k>n,1/k^5).at n=7A083560
- E.g.f. A(x) satisfies: A(x) = 1 + Series_Reversion( Integral A(-x) dx ).at n=8A144005
- Numbers k whose decimal expansion can be split into at least two parts whose binary equivalents can be concatenated (in the same order) to form the binary expansion of the original number k.at n=22A237041
- Triangle read by rows: numerators of coefficients of the Hirzebruch L-polynomials L_n expressing the signature of a 4n-dimensional manifold in terms of its Pontrjagin numbers (as in Hirzebruch Signature Theorem).at n=27A237111
- a(n) = floor(1/(zeta(5) - Sum_{h=1..n} 1/h^5)).at n=6A248234
- Number of (n+2)X(2+2) 0..3 arrays with every 3X3 subblock row and column sum equal to 2 3 4 6 or 7 and every 3X3 diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=6A252161
- Number of (n+2)X(7+2) 0..3 arrays with every 3X3 subblock row and column sum equal to 2 3 4 6 or 7 and every 3X3 diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=1A252166
- T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum equal to 2 3 4 6 or 7 and every 3X3 diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=29A252167
- T(n,k)=Number of (n+2)X(k+2) 0..3 arrays with every 3X3 subblock row and column sum equal to 2 3 4 6 or 7 and every 3X3 diagonal and antidiagonal sum not equal to 2 3 4 6 or 7.at n=34A252167
- Numbers k such that [prime(k), prime(k+1), prime(k+2)] = [1, 2, 3] mod 11.at n=19A302767
- a(n) = 36*n^2 - 8*n - 2 (n >=1).at n=18A304834
- Number of derangements of [n] having no adjacent 2-cycles, no adjacent 3-cycles, no adjacent 4-cycles and no adjacent 5-cycles.at n=8A370324