15867
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 24024
- Proper Divisor Sum (Aliquot Sum)
- 8157
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10080
- Möbius Function
- 0
- Radical
- 5289
- Omega Function (Ω)
- 4
- 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
- 76
- 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
- no
- Odd
- yes
Appears in sequences
- From George Gilbert's marks problem: jumping 7 marks at a time (final positions).at n=13A019998
- Trajectory of 3 under map n->13n+1 if n odd, n->n/2 if n even.at n=30A037104
- From Renyi's "beta expansion of 1 in base 3/2": sequence gives a(1), a(2), ... where x(n) = a(n)/2^n, with 0 < a(n) < 2^n, a(1) = 1, a(n) = 3*a(n-1) modulo 2^n.at n=13A058842
- Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of k; set a(n) = -1 if some fraction i/n never appears.at n=8A066848
- Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of k; set a(n) = -1 if some fraction i/n never appears.at n=17A066848
- a(n) = number of primes of the form x^2 + 1 <= 2^n.at n=35A083847
- a(1) = 3, a(n) = a(n-1) + 4*(a(n-1)-floor(a(n-1)^(1/3))^3).at n=20A096297
- 4-almost primes equal to the product of two successive semiprimes.at n=41A108215
- a(n) = A130179(n)/81.at n=19A130085
- First trisection of A028560.at n=41A147651
- a(n) = 81*n^2 - 9.at n=13A157909
- a(n) = 196*n^2 - n.at n=8A158003
- Number of primes of the form x^2 + 1 < 2^n.at n=35A174246
- a(0)=a(1)=1, a(n) = least k > a(n-1) such that k*a(n-2) is a triangular number.at n=32A214961
- Number of genus 3 unsensed hypermaps with n darts.at n=8A215017
- Hilltop maps: number of n X 2 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..2 n X 2 array.at n=6A218313
- Hilltop maps: number of nX7 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..2 nX7 array.at n=1A218318
- T(n,k)=Hilltop maps: number of nXk binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..2 nXk array.at n=29A218319
- T(n,k)=Hilltop maps: number of nXk binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..2 nXk array.at n=34A218319
- Hilltop maps: number of nX7 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..2 nX7 array.at n=1A219062