13923
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 26208
- Proper Divisor Sum (Aliquot Sum)
- 12285
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6912
- Möbius Function
- 0
- Radical
- 4641
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
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
- 58
- 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
- a(n) = (4*n+1)*(4*n+3).at n=29A001539
- Expansion of Product_{m>=1} ((1+q^(2*m-1))/(1+q^(2*m)))^7.at n=18A029844
- Numbers n such that n^2 - 1 is expressible as the sum of two nonzero squares in exactly one way.at n=34A050797
- Maximal value of products of partitions of n into powers of distinct primes (powers of 1 and 2 excluded).at n=46A051704
- Number of times n occurs in A000195.at n=9A064780
- Floor(X/Y) where X = concatenation of the (n+1)-st even number through the (2n)-th even number and Y = concatenation of first n even numbers.at n=15A067091
- Numbers k such that sigma(prime(k) + 1) == 0 (mod k).at n=41A067759
- Denominator of 2*Sum(C(n,w)/(2*w+1),w=0..n/2-1)+C(n,n/2)/(n+1) if n is even, or of 2*Sum(C(n,w)/(2*w+1),w=0..(n-1)/2) if n is odd.at n=25A085569
- Numbers with exactly one arithmetic progression of four successive divisors (not necessarily consecutive).at n=15A094530
- a(n) = n*(n+1)*(n+2)*(n+4)*(n+23)/120.at n=12A101855
- a(n) = binomial(n+2,2)*binomial(n+6,2).at n=12A104473
- Gaussian column reduction of Hankel matrix for central Delannoy numbers.at n=30A118384
- Numbers n for which nontrivial positive magic squares of exactly 10 different orders with magic sum n exist. For a definition of nontrivial positive magic squares, see A125005.at n=34A125017
- Triangle H(n,j) (n=1,2,3,..., j=2,3,4,...) read by rows: let X(k,l,n) := Stirling2(n,k)*Stirling2(k,l) for 1<=k<=n and 1<=l<=k. Then H(n,j)= sum_{k+l=j, 1<=k<=n and 1<=l<=k} X(k,l,n).at n=53A136206
- Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1000-1111-0010 pattern in any orientation.at n=13A146403
- Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 1000-1111-0110 pattern in any orientation.at n=10A146611
- a(n) = (n-5)*(n-6)*(n-7)*(n-16)/24.at n=25A167543
- Product of odd prime anti-factors < n, with multiplicity.at n=58A171487
- Numbers that take a record number of steps to appear in A181391.at n=45A171863
- Odd long legs `B` of more than one primitive Pythagorean triangle.at n=21A179271