15409
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16240
- Proper Divisor Sum (Aliquot Sum)
- 831
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 14580
- Möbius Function
- 1
- Radical
- 15409
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 146
- 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 number of integers m which take n steps to reach 1 in '3x+1' problem.at n=43A005186
- Pseudoprimes to base 15.at n=25A020143
- Pseudoprimes to base 54.at n=38A020182
- Strong pseudoprimes to base 15.at n=5A020241
- Strong pseudoprimes to base 54.at n=12A020280
- Number of partitions of 1/n into 4 reciprocals of positive integers.at n=30A020327
- a(n) = 5^n - n^3.at n=6A024052
- Numbers m such that sigma(m+1)+sigma(m-1) = 5*phi(m).at n=16A067242
- Numbers k such that phi(k) divides (sigma(k+1) + sigma(k-1)).at n=41A067244
- Smallest squarefree integer k such that Q(sqrt(k)) has class number n.at n=18A081363
- Smallest d such that real quadratic field with discriminant d has class number n.at n=18A081364
- G.f.: (1-2*x^2)/(1-x-2*x^2-x^3).at n=14A108122
- a(n)= +a(n-3) +2*a(n-6) +a(n-9).at n=38A109531
- Odd numbers n for which 17 is the smallest i (>= 1) with Jacobi symbol J(i,n) getting either a value 0 or -1.at n=17A112077
- Semiprimes in A056105.at n=29A113519
- Number of binary strings of length n with no substrings equal to 000, 001, or 010.at n=24A164316
- Numerator of H(n+4) - H(n), where H(n) = Sum_{k=1..n} 1/k.at n=26A189642
- a(n) = (n^3 - 2*n^2 + 3*n + 2)/2.at n=32A189890
- Least positive x in the Diophantine equation x^3 + y^3 = n*z^3 (with x >= y and y != 0).at n=32A190356
- Monotonic ordering of nonnegative differences 5^i-6^j, for 40>= i>=0, j>=0.at n=18A192193