15540
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 48
- Divisor Sum
- 51072
- Proper Divisor Sum (Aliquot Sum)
- 35532
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 3456
- Möbius Function
- 0
- Radical
- 7770
- Omega Function (Ω)
- 6
- Little Omega Function (ω)
- 5
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 40
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Glaisher's function H'(4n+1) (18 squares version).at n=19A002610
- a(n) = 2*binomial(n,3).at n=37A007290
- Perimeters of more than one primitive Pythagorean triangle.at n=25A024408
- Denominator of b(n)-b(n+1), where b(n) = n/((n+1)(n+2)) = A026741/A045896.at n=33A051713
- Number of positive integers <= 2^n of form x^2 + 15 y^2.at n=17A054229
- Saint-Exupéry numbers: ordered products of the three sides of Pythagorean triangles.at n=12A057096
- Triangle T(n,k) of number of unilaterally connected digraphs on n labeled nodes and with k arcs, k=0..n*(n-1).at n=30A057275
- Sum of squares of entries of Wilkinson's eigenvalue test matrix of order 2n+1.at n=28A059834
- Ordered products of the sides of primitive Pythagorean triangles.at n=6A063011
- Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,13.at n=9A064243
- a(n) = binomial(2*n,n) mod ((n+1)*(n+2)*(n+3)).at n=33A065345
- (Sum of digits of n)^5 - (sum of digits^5 of n).at n=34A069965
- (Sum of digits of n)^5 - (sum of digits^5 of n).at n=43A069965
- Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=24A070237
- Number of conjugacy classes in the group GL(3,Z_n).at n=24A086768
- Integers that are Rhonda numbers to base 9.at n=0A100973
- Numbers k such that the k-th triangular number plus the reverse of k gives a square.at n=8A113799
- a(n) is the determinant of the 3 X 3 matrix with entries the 9 consecutive primes starting with the n-th prime.at n=41A117330
- Icosagonal numbers divisible by 20.at n=9A117798
- Triangle where T(n,k) = n!*[x^k] ( x/(2*x + log(1-x)) )^(n+1), for n>=k>=0, read by rows.at n=24A118787