12123
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 18000
- Proper Divisor Sum (Aliquot Sum)
- 5877
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8064
- Möbius Function
- 0
- Radical
- 1347
- Omega Function (Ω)
- 4
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 81
- 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
- Multiplicity of highest weight (or singular) vectors associated with character chi_146 of Monster module.at n=39A034534
- Number of partitions with at most one part divisible by 5.at n=34A039905
- Take n points in general position in the plane; draw all the (infinite) straight lines joining them; sequence gives number of connected regions formed.at n=19A055503
- Coefficients of monic primitive irreducible polynomials over GF(4) listed in lexicographic order.at n=39A058952
- Number of orbits of the group of units of Z/(n) acting naturally on the 4-subsets of Z/(n).at n=48A063381
- Coefficients of power series A(x) such that n-th term of A(x)^n = n! x^(n-1) for n > 0.at n=8A075834
- a(n) = A076969(n)^(1/3).at n=37A076970
- Sum of first n 6-almost primes.at n=26A086052
- Triangle, read by rows, such that the initial terms of the binomial transform of the n-th row forms the n-th row of triangle A059438 transposed (permutations of [1..n] with k components).at n=43A091063
- Indices n such that the 3 X 3 matrix with components (row by row) prime(n+k), 0 <= k <= 8, has zero determinant.at n=16A117345
- Describe prime factorization of n (primes in ascending order and with repetition) (method A - initial term is 2).at n=44A123132
- Numbers k such that k, k+1, k+2 and k+3 are products of 4 primes.at n=4A124728
- Sorted list of strings that can be obtained by starting with 123 and repeatedly doubling any substring in place.at n=7A135475
- Sorted list of primitive strings that can be obtained by starting with 123 and repeatedly doubling any substring in place.at n=1A135479
- a(1)=4. a(n) = a(n-1) + n, if a(n-1)+n is composite. Otherwise a(n) = a(n-1)*n.at n=26A175459
- Number of (n+2)X(n+2) symmetric binary matrices without the pattern 0 1 1 diagonally, vertically, antidiagonally or horizontally.at n=3A190538
- Numbers n for which A222085(n)=A222085(n+1).at n=16A222088
- The number of overpartitions of n with restricted odd differences.at n=29A260890
- Words over an alphabet of size 9 that are in standard order with at least one letter repeated.at n=39A273977
- Sequence is an irregular triangle read by rows with zeros removed where T(n,k) is the number of compositions of n whose standard factorization into Lyndon words has k distinct factors.at n=50A299072