8215
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 10368
- Proper Divisor Sum (Aliquot Sum)
- 2153
- 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
- 6240
- Möbius Function
- -1
- Radical
- 8215
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- Ramanujan's approximation to population of x^2 + y^2 <= 2^n.at n=15A000691
- exp(tan(x)-sinh(x))=1+1/3!*x^3+15/5!*x^5+10/6!*x^6+271/7!*x^7...at n=9A013449
- a(n) = Sum_{k=0..floor(n/2)} T(n-k,k), T given by A026747.at n=17A026757
- a(n+1) = [ A*a(n)+B ]/p^r, where p^r is the highest power of p diving [ A*a(n)+B ] and p=2, A=2.00013, B=3.0.at n=24A029580
- Numbers k such that k^2 is palindromic in base 3.at n=40A029984
- Largest coefficient in expansion of Product_{i=1..n} (1 + (-q)^i).at n=18A039828
- Numbers whose base-5 representation contains exactly two 0's and three 3's.at n=22A045198
- a(n) = Sum_{d|n} d*prime(d).at n=42A061150
- Next-to-middle coefficient in expansion of Product_{k=1..n} (1 + x^k).at n=18A068202
- Numbers n such that the partition function A000041(k) is even and odd the same number of times for 0 <= k <= n.at n=29A098936
- Expansion of (1-2x)^2/((1-x)^2(1-2x-x^2)^2).at n=10A108360
- Number of solutions to +- 1 +- 2 +- .. +- n = 2.at n=19A113036
- a(n) = 2^(n+1) + 2*n - 1.at n=12A131898
- a(n) = (2*n+1)*(6*n-1).at n=26A179741
- The number of biconnected squaregraphs with n vertices.at n=19A194092
- Number of connected cyclic conjugacy classes of subgroups of the symmetric group.at n=52A218970
- Number of 4 X n arrays of the minimum value of corresponding elements and their horizontal or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..1 4 X n array.at n=34A220034
- Coefficient array for powers of x^2 of polynomials appearing in a generalized Melham conjecture on alternating sums of fifth powers of Chebyshev S polynomials with odd indices.at n=24A220671
- a(n) = 6*n^2 + 1.at n=37A227776
- Numbers of undirected cycles in the n-queen graph.at n=2A234626