13863
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18488
- Proper Divisor Sum (Aliquot Sum)
- 4625
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9240
- Möbius Function
- 1
- Radical
- 13863
- 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
- 151
- 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
- a(n) = 10000*log(n) rounded to nearest integer.at n=3A004244
- a(n) = ceiling(10000*log(n)).at n=3A004245
- 11*n^2 + 11*n + 3.at n=35A006222
- Poincaré series [or Poincare series] of Lie algebra associated with a certain braid group.at n=14A007990
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 78.at n=33A031576
- Number of untouchable numbers <= 10^n.at n=4A057978
- Exp(n) is further from an integer than any previous exp(k) for 1 <= k < n.at n=19A080053
- Numbers n such that (n+j) mod (2+j) = 1 for j from 0 to 5 and (n+6) mod 8 <> 1.at n=16A096024
- a(n) = round(10000*log(n/10)).at n=39A104077
- Odd winning positions in Fibonacci nim.at n=34A120904
- a(n) is the smallest semiprime such that difference between a(n) and next semiprime, b(n), is n.at n=21A131109
- a(n) = least member of A006881 whose difference from the following one equals n, or 0 if no such semiprime exists.at n=21A140784
- Number of n X 5 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.at n=6A207108
- Number of 7Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.at n=4A207116
- Number of (n+2) X (1+2) 0..1 arrays with each 3 X 3 subblock having clockwise perimeter pattern 00010101 00100101 or 01010101.at n=10A261258
- a(n) is the smallest semiprime followed by gap (to the next semiprime) equal to n-th semiprime.at n=7A278349
- Number of connected (non-null) induced subgraphs in the n-Andrásfai graph.at n=4A287995
- Numbers k such that (305*10^k + 1)/9 is prime.at n=17A295398
- Take a squarefree semiprime and take the difference of its prime factors. If it is a squarefree semiprime repeat the process. Sequence lists the squarefree semiprimes that generate other squarefree semiprimes only in the first k steps of this process. Case k = 4.at n=27A296811
- a(1) = 1; a(n+1) = Sum_{d|n} sigma(n/d)*a(d), where sigma = sum of divisors (A000203).at n=32A307817