13466
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 20202
- Proper Divisor Sum (Aliquot Sum)
- 6736
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6732
- Möbius Function
- 1
- Radical
- 13466
- 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
- 45
- 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
- yes
- Odd
- no
Appears in sequences
- Number of partitions of n into parts not of form 4k+2, 20k, 20k+7 or 20k-7. Also number of partitions in which no odd part is repeated, with at most 3 parts of size less than or equal to 2 and where differences between parts at distance 4 are greater than 1 when the smallest part is odd and greater than 2 when the smallest part is even.at n=51A036027
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 21.at n=19A051986
- Partial sums of A102540 (primes that are not Chen primes).at n=38A115606
- Number of ways to place 3 nonattacking bishops on a 3 X n board.at n=15A172207
- Triangle t(n,m,k) = binomial(n, m) - k*(binomial(n, m)*binomial(n+1, m)/(m+1)) + k*Eulerian(n+1, m) with k = 6.at n=24A178347
- Number of (w,x,y,z) with all terms in {1,...,n} and |w-x|=2|x-y|+2|y-z|.at n=38A212576
- Number of Dyck paths of semilength n avoiding the pattern U^4 D^4 U D.at n=20A225691
- Numerators of continued fraction transform of e; see Comments.at n=7A229595
- Number of (7+2) X (n+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=10A252391
- a(1) = a(2) = 2; a(n) = a(n-1) + gpf(a(n-2)), where gpf is greatest prime factor.at n=39A258125
- Numbers k such that (35*10^k - 377)/9 is prime.at n=17A295967
- Numbers k not ending in zero that are a substring of k*(k+1).at n=10A305670
- a(n) = floor( (4/5)*( (9/4)^(n+1)-1 ) ).at n=11A361506
- Semiprimes s = A001358(k) such that k, s - k and s + k are also semiprimes.at n=48A383468