6509
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 6816
- Proper Divisor Sum (Aliquot Sum)
- 307
- 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
- 6204
- Möbius Function
- 1
- Radical
- 6509
- 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
- 75
- 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
- Coordination sequence for alpha-Mn, Position Mn2.at n=21A009951
- Numbers k such that the continued fraction for sqrt(k) has period 72.at n=19A020411
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 32 ones.at n=40A031800
- First differences of A037260.at n=27A037261
- Numerators of continued fraction convergents to sqrt(340).at n=7A041642
- Numbers having three 5's in base 8.at n=32A043443
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 24.at n=29A051965
- Semiprimes p1*p2 such that p2>p1 and p2 mod p1 = 7.at n=33A064905
- Sum of the first moments of all partitions of n with weights starting at 0.at n=16A066185
- For even n, a(n) = a(n-2) + a(n-1) + 2^(n/2-2), n>2. For odd n, a(n) = a(n-2) + a(n-1).at n=18A079289
- Highly cototient numbers: records for a(n) in A063741.at n=46A100827
- Numbers k such that k and k^2 together contain all ten digits.at n=17A122477
- Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1100-1100-0111 pattern in any orientation.at n=13A146696
- Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1101-0111-0001 pattern in any orientation.at n=13A147237
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, 0), (0, 0, 1), (0, 1, -1), (1, 0, 1)}.at n=7A150401
- a(n) = Sum_{k=1..n} k*lcm(k,k')/gcd(k,k'), where k' is arithmetic derivative of k.at n=18A190122
- Number of compositions of n where differences between neighboring parts are in {-2,2}.at n=60A214254
- Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 557", based on the 5-celled von Neumann neighborhood.at n=44A272924
- Smallest positive number whose residues modulo the first n primes are all different but whose residues modulo the first n+1 primes are not all different.at n=16A279074
- Number of weakly unimodal compositions of n in which the greatest part occurs exactly nine times.at n=58A320320