12885
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 20640
- Proper Divisor Sum (Aliquot Sum)
- 7755
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6864
- Möbius Function
- -1
- Radical
- 12885
- Omega Function (Ω)
- 3
- 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
- 24
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Number of unlabeled disconnected series-parallel posets with n nodes.at n=9A007454
- Positive numbers k such that k and 2*k are anagrams in base 9 (written in base 9).at n=23A023079
- a(n) is the smallest index m such that Sum_{k=2..m} 1/PrimePi(k) >= n, where PrimePi()=A000720().at n=39A074633
- To compute a(n) we first write down 5^n 1's in a row. Each row takes the rightmost 5th part of the previous row and each element in it equals sum of the elements of the previous row starting with the first of the rightmost 5th part. The single element in the last row is a(n).at n=4A109057
- a(n) = prime(n)_prime(n).at n=29A122622
- a(n) = n^3 + sum((-1)^j*a(j)); for j=1 to n-1; a(1)=1.at n=38A153286
- Number of 11X2 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 11 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=11A192712
- Odd numbers producing 5 odd numbers in the Collatz iteration.at n=43A198588
- Odd numbers producing 20 even numbers in the Collatz iteration.at n=38A199818
- Triangle of coefficients of polynomials v(n,x) jointly generated with A208761; see the Formula section.at n=52A208762
- Largest number of the form C(n,x) + C(n,y) + C(n,z) where x + y + z = n.at n=15A209083
- Numbers m such that (4^m + 5) / 3 is prime.at n=19A261539
- Pseudoprimes to base 9, written in base 9.at n=48A262154
- Numbers n such that 2*n*3^n + 1 is prime.at n=27A266694
- Number of quadruples (p_1, ..., p_4) of positive integers such that p_{i-1} <= p_i <= n^(i-1).at n=5A354608
- Number of partitions of n that contain more nonprime parts than prime parts.at n=37A355158
- Number A(n,k) of n-tuples (p_1, p_2, ..., p_n) of positive integers such that p_{i-1} <= p_i <= k^(i-1); square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=49A355576
- a(n) = Sum_{d|n} (-1)^(n/d-1) * binomial(d+2,3).at n=43A366813
- Triangle read by rows: T(n,k) = number of free hexagonal polyominoes with n cells, where the maximum number of cells on any lattice line is k. The term "lattice line" here means a line running through the cell centers and midpoints of their sides.at n=60A378014
- The reversing binary representation of the sum of the divisors of the n-th odd square: a(n) = A065621(A379223(n)).at n=33A379224