6531
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 9984
- Proper Divisor Sum (Aliquot Sum)
- 3453
- 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
- 3720
- Möbius Function
- -1
- Radical
- 6531
- 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
- 137
- Smith Number
- yes
- 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
- a(n) = Sum_{k=1..n} k*phi(k).at n=30A011755
- Expansion of 1/(1-x^3-x^4-x^5).at n=36A017818
- Number of chord diagrams of degree n with an isolated chord of length 1.at n=6A018193
- a(n) = a(n-1) + a(n-2) + 1 for n>1, a(0)=0, a(1)=5.at n=16A022310
- a(n) = [ a(n-1)/a(1) + a(n-3)/a(3) + a(n-5)/a(5) + ... ], for n >= 3.at n=35A022871
- "BGK" (reversible, element, unlabeled) transform of 0,1,1,1,...at n=32A032060
- a(1) = 8; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=37A046258
- T(n,n), array T as in A047120.at n=8A047122
- 33-gonal numbers: n(31n-29)/2.at n=21A098923
- First element of first run of exactly n consecutive numbers not of form x^2+y^2.at n=12A104271
- Numbers n such that googol - n is prime.at n=21A108251
- Nonprimes k > 0 such that 6^k==6 (mod k).at n=42A122783
- Numbers k such that 120*k + 1 is a term in A163573.at n=28A163625
- Partial sums of A023201.at n=40A172295
- 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=23A178347
- 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=25A178347
- Numbers n such that (n^6 + 1091)/4 is prime.at n=5A181112
- Iterate the map in A006369 starting at 144.at n=47A185589
- Position of 2^n in A051037 (5-smooth numbers).at n=50A188425
- a(n) = 3*a(n-1) + 46*a(n-2) + a(n-3) with a(0)=2, a(1)=5, a(2)=106.at n=4A215572