15415
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
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18504
- Proper Divisor Sum (Aliquot Sum)
- 3089
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12328
- Möbius Function
- 1
- Radical
- 15415
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 71
- 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
- From expansion of falling factorials.at n=11A005492
- Fibonacci sequence beginning 1, 15.at n=16A022105
- Numbers k such that 2*10^k + R_k + 8 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=8A102950
- Moessner triangle based on A000217.at n=25A125777
- The number of dominance pairs of integer partitions of n according to either/or dominance order, where dominance between two partitions x and y means that x is majorized by y or y is majorized by x.at n=14A182988
- Number of (n+1) X 8 0..2 matrices with each 2 X 2 subblock idempotent.at n=11A224675
- Smallest positive integer in the primitive cycle(s) under iteration by the 3x-k function, where k=A226630(n).at n=25A226633
- Number of connected planar regular graphs on 2n vertices with girth at least 4.at n=9A255600
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 7", based on the 5-celled von Neumann neighborhood.at n=27A270012
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 7", based on the 5-celled von Neumann neighborhood.at n=28A270012
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 261", based on the 5-celled von Neumann neighborhood.at n=28A271062
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 337", based on the 5-celled von Neumann neighborhood.at n=28A271287
- Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 475", based on the 5-celled von Neumann neighborhood.at n=30A288500
- Irregular table: n-th row polynomial given by the formal power series expansion of Sum_{k >= 0} (1 + q)^(n*k + k*(k+1)/2)* Product_{j = 1..k} (1 - (1 + q)^j), n >= 1.at n=45A340880
- a(n) = 2*(-i)^n*(n*sin(c*(n+1)) - i*sin(-c*n))/sqrt(5) where c = arccos(i/2).at n=15A354044
- a(n) = Sum_{j=1..n} Sum_{k=1..n} tau(j*k).at n=36A372674