6519
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 9072
- Proper Divisor Sum (Aliquot Sum)
- 2553
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4160
- Möbius Function
- -1
- Radical
- 6519
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 49
- 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 k such that the period of the continued fraction for sqrt(k) contains exactly nine 1's.at n=20A020445
- a(n) = [ (3rd elementary symmetric function of P(n))/(first elementary symmetric function of P(n)) ], where P(n) = {first n+2 primes}.at n=10A024453
- a(n) = (d(n)-r(n))/5, where d = A026063 and r is the periodic sequence with fundamental period (1,4,0,0,0).at n=47A026065
- a(n) = Sum_{m=1..n, k=1..m} T(m,k), array T as in A049834.at n=36A049836
- Sum_{k<=n} (sigma(k)^2), where sigma(k) denotes the sum of the divisors of k A000203.at n=18A072379
- Total number of parts smaller than the largest part, in all partitions of n.at n=21A116686
- G.f. A(x) equals the limit of the composition of functions (x+x^n); let F_1(x) = x, F_{n+1}(x) = F_n(x+x^(n+1)), then A(x) = limit F_n(x): A(x) = x o x+x^2 o x+x^3 o ... o x+x^n o...at n=17A119470
- Row sums of triangle A136791.at n=6A136792
- Numbers n such that primorial(n)/2 - 512 is prime.at n=18A139454
- Wiener index of the n-sun graph.at n=39A180863
- Wechsler's "convex-hull polyominoes": convex hull contains no additional grid points.at n=15A181785
- Number of nXnXn 0..6 triangular arrays with each element x equal to the number its neighbors equal to 6,0,1,2,2,0,1 for x=0,1,2,3,4,5,6.at n=5A197664
- Number of (w,x,y) with all terms in {0,...,n} and the numbers w,x,y,|w-x|,|x-y| not distinct.at n=26A213491
- Triangle read by rows: T(n,k) is the coefficient in the transformation Sum_{k=0..n} (k+1)*x^k = Sum_{k=0..n} T(n,k)*(x-k)^k.at n=23A247237
- Sum of divisors of n^2 that do not divide n.at n=47A320059
- Let t_k denote the triangular number k*(k+1)/2. Suppose 0 < x < y < z are integers satisfying t_x + t_y = t_p, t_y + t_z = t_q, t_x + t_z = t_r, for integers p,q,r. Sort the triples [x,y,z] first by x, then by y. Sequence gives the values of z.at n=38A332590
- Integers k that are equal to the sum of at least two distinct of their anagrams, which must have the same number of digits as k.at n=28A384433