6511
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 6912
- Proper Divisor Sum (Aliquot Sum)
- 401
- 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
- 6112
- Möbius Function
- 1
- Radical
- 6511
- 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
- a(n) is the solution to the postage stamp problem with n denominations and 5 stamps.at n=16A001215
- a(n) = n^2 written backwards.at n=33A002942
- a(n) = (n + 3)*(n^2 + 6*n + 2)/6.at n=31A005286
- a(n) is the sum over all floor(k^3/n), k=0 to n inclusive.at n=28A014818
- Sequence satisfies T^2(a)=a, where T is defined below.at n=50A027596
- Arrange digits of squares in descending order.at n=34A028908
- Number of distinct quadratic residues mod 5^n.at n=6A039302
- Numerators of continued fraction convergents to sqrt(830).at n=5A042602
- Numbers whose base-5 representation contains exactly two 0's and three 2's.at n=29A045183
- a(1) = 9; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=39A046259
- Numbers k such that sum of factorials of digits of k equals pi(k) (A000720).at n=3A049529
- Number of positive integers <= 2^n of form 5 x^2 + 6 y^2.at n=16A054176
- Numbers k such that k and its reversal are both multiples of 17.at n=21A062906
- Non-palindromic number and its reversal are both multiples of 17.at n=13A062915
- Semiprimes p1*p2 such that p2 mod p1 = 9, with p2 > p1.at n=31A064907
- Centered 14-gonal numbers.at n=30A069127
- a(1) = 2; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=44A074338
- n^2 read backwards, for n = 51, 50, 49, ..., 1.at n=17A080334
- Numbers n such that n^2+n+41 (Euler's "prime generating polynomial") is not squarefree.at n=40A097823
- Numbers k such that 8*10^k + 6*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=12A103088