13605
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 21792
- Proper Divisor Sum (Aliquot Sum)
- 8187
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7248
- Möbius Function
- -1
- Radical
- 13605
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 89
- 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
- Numbers whose base-7 representation contains exactly four 4's.at n=28A043412
- Numbers k such that 10*7^k + 1 is prime.at n=18A057437
- Numbers in which starting from most significant digit the n-th digit is obtained by adding n to the (n-1)-st digit (the digit to the left of it) and then ignoring the carry. Alternately the n-th digit starting from the most significant digit is the n-th triangular number mod 10.at n=4A069511
- Trajectory of 8 under iteration of the map k -> A087712(k).at n=21A144813
- Numbers n such that 2^n divided by the number of digits of 2^n is an integer.at n=43A158520
- a(n) = 3*a(n-1) - a(n-3), with a(0) = 3, a(1) = 3, and a(2) = 9.at n=9A215885
- Sum of largest parts of all partitions of n into an even number of parts.at n=27A222048
- Number of nX4 integer arrays with each element equal to the number of horizontal and vertical neighbors differing from itself by exactly one.at n=19A266077
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 441", based on the 5-celled von Neumann neighborhood.at n=25A272223
- Partial sums of number of overpartitions (A015128).at n=18A277643
- a(n) = 424*2^n + 37.at n=5A277989
- Ground state degeneracy of a periodic chain for angle theta = 3*Pi/2.at n=6A299798
- T(n,k) is the number of connected unlabeled posets with n elements and rank k: triangle read by rows.at n=51A342500
- Number of integer partitions of n with non-integer median of multiplicities.at n=43A360690
- Expansion of e.g.f. (1/x) * Series_Reversion( x/(x + exp(x^2/2)) ).at n=6A370877
- Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of edges in H_n.at n=14A370979