12811
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13392
- Proper Divisor Sum (Aliquot Sum)
- 581
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12232
- Möbius Function
- 1
- Radical
- 12811
- 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
- 169
- 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
- no
- Odd
- yes
Appears in sequences
- Numbers k such that the continued fraction for sqrt(k) has period 100.at n=34A020439
- Number of prime powers (p^2, p^3, ...) <= 2^n.at n=33A036386
- Base 8 palindromes that start with 3.at n=26A043023
- Numbers n of the form k + reverse(k) for exactly two k.at n=33A072040
- Total number of palindromic primes in base 8 with n digits.at n=10A117786
- Numbers k such that tau(k) = tau(k+1) mod 691, where tau is Ramanujan's tau function A000594.at n=18A121733
- Multiples of 23 whose digit reversal + 1 is also a multiple of 23.at n=21A166393
- The largest number m such that sigma(m) = A007368(n), where A007368(n) = the smallest k such that sigma(x) = k has exactly n solutions.at n=22A184394
- Partial sums of A007202 (crystal ball sequence for hexagonal close-packing).at n=10A186707
- Number of (w,x,y,z) with all terms in {1,...,n} and w*x+y*z<=n^2.at n=11A212150
- Number of (w,x,y,z) with all terms in {1,...,n} and |x-y|=n-w+|y-z|.at n=29A212684
- Composites in base 10 that remain composite in exactly four bases b, 2 <= b <= 10, expansions interpreted as decimal numbers.at n=7A256354
- Noncube integers n such that n^2 + 1 is the sum of 2 positive cubes.at n=8A267119
- G.f.: 1 + Sum_{n=-oo..+oo, n<>0} (x - x^n)^n / (1 - (x - x^n)^n).at n=20A294677
- Partial sums of A299272.at n=21A299273
- MM-numbers of capturing, non-nesting multiset partitions (with empty parts allowed).at n=16A326260
- Number of compositions (ordered partitions) of n into distinct parts >= 8.at n=63A339109
- a(n) = n! * Sum_{k=0..floor(n/2)} (n - 2*k)^k/(n - 2*k)!.at n=7A356628
- Centered heptagonal numbers which are semiprime.at n=21A381960