13481
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 15624
- Proper Divisor Sum (Aliquot Sum)
- 2143
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11520
- Möbius Function
- -1
- Radical
- 13481
- 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
- yes
- 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
- Pseudoprimes to base 60.at n=29A020188
- Quasi-Carmichael numbers to base 6: squarefree composites n such that (n,2*3*5) = 1 and prime p|n ==> p-6|n-6.at n=0A029557
- For n>0, a(n) is the least quasi-Carmichael number to base n; a(0) = least composite squarefree integer.at n=6A029590
- Numbers n such that n and n-1 are differences between 2 positive cubes in at least one way.at n=15A038595
- Difference between partial sums of partition numbers (A026905) and partial sums of numbers of partitions into distinct parts (A026906).at n=26A056870
- Numbers k such that (k / sum of digits of k) and (k+1 / sum of digits of k+1) are both semiprime.at n=24A085774
- Numbers n such that A001414(n) = sum of squared digits of n.at n=24A094908
- a(0)=1, a(1)=1, a(n) = 9*a(n/2) for even n >= 2, and a(n) = 8*a((n-1)/2) + a((n+1)/2) for odd n >= 3.at n=27A116526
- Numerator of Euler(n, 4/25).at n=3A156968
- Number of distinct sums of reciprocals of parts of partitions of n.at n=38A212187
- Number of (w,x,y,z) with all terms in {1,...,n} and 2w+2x=3y+3z.at n=40A212567
- Numbers n such that sum of squares of digits of n equals the sum of prime divisors of n.at n=29A217390
- G.f.: Sum_{n>=0} x^n * (1+x)^(n^2) / (1 + x*(1+x)^n)^n.at n=10A221546
- a(n) = Sum_{k=0..3} f(n+k)^2 where f=A130519.at n=21A238604
- Number of partitions of n containing m(4) as a part, where m denotes multiplicity.at n=40A240489
- Number of length 3 0..n arrays with each partial sum starting from the beginning no more than sqrt(3) standard deviations from its mean.at n=23A244942
- Numbers n such that n!3 + 3 is prime, where n!3 = n!!! is a triple factorial number (A007661).at n=38A249400
- Expansion of (1 + 6*x + x^2 + 12*x^3 - 2*x^4)/((1 - x)^4*(1 + x)^3).at n=32A268579
- Nonsemiprimes in A306097 = A121707 \ A267999.at n=15A321488
- Expansion of Product_{k>=1} (1 + x^k) * (1 + x^(2*k)) * (1 + x^(3*k)) * (1 + x^(4*k)) * (1 + x^(5*k)).at n=29A327047