15505
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 21312
- Proper Divisor Sum (Aliquot Sum)
- 5807
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10608
- Möbius Function
- -1
- Radical
- 15505
- 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
- 146
- 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
- A nonlinear recurrence.at n=40A003073
- Expansion of e.g.f. exp(arctan(x) - log(x+1)).at n=8A013459
- Pseudoprimes to base 13.at n=40A020141
- Strong pseudoprimes to base 34.at n=13A020260
- Numbers k such that the continued fraction for sqrt(k) has period 98.at n=29A020437
- a(n) = n*(n^2+3*n-1)/3.at n=35A084990
- Triangle, read by rows, of the coefficients of [x^k] in G100234(x)^n such that the row sums are 6^n-1 for n>0, where G100234(x) is the g.f. of A100234.at n=32A100235
- Round(1000*x), where x is the solution to x = 3^(n-x).at n=18A103537
- Number of ways to write n as an ordered sum of 1s, 2s, 3s and 4s such that no 2 precedes any 1 and no 3 precedes any 1 or 2.at n=25A123569
- Triangle, read by rows, T(n, k) = binomial(4*n, 3*k) + binomial(4*n, 3*(n-k)).at n=15A154918
- Triangle, read by rows, T(n, k) = binomial(4*n, 3*k) + binomial(4*n, 3*(n-k)).at n=20A154918
- G.f.: A(x) = 1 + x/exp( Sum_{k>=1} (A((-1)^k*x) - 1)^k/k ).at n=19A157674
- 28-gonal numbers: a(n) = n*(13*n - 12).at n=35A161935
- Numbers n such that 30n+{11, 13, 17, 19, 23} are 5 consecutive primes.at n=21A182279
- Number of 5 X n 0..1 arrays with rows nondecreasing and antidiagonals unimodal.at n=7A224136
- a(n) = n^4/8 + (5*n^3)/12 - n^2/8 - (5*n)/12 + 1.at n=19A226639
- a(n) = Sum_{i=1..n} ( Product_{k|i} d(k) ), where d(n) = A000005(n).at n=31A237349
- Number of partitions of n, where the difference between the number of odd parts and the number of even parts is 3.at n=48A240012
- Expansion of (Sum_{k>=0} x^(k^4))^19.at n=19A282288
- Solution (a(n)) of the complementary equation in Comments.at n=41A298877