8509
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8704
- Proper Divisor Sum (Aliquot Sum)
- 195
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8316
- Möbius Function
- 1
- Radical
- 8509
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 78
- 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
- Numbers k where |cos(k)| (or |cosec(k)| or |cot(k)|) decreases monotonically to 0; also numbers k where |tan(k)| (or |sec(k)|, or |sin(k)|) increases.at n=29A004112
- a(n) = floor( n*(n-1)*(n-2)/28 ).at n=63A011910
- Eight iterations of Reverse and Add are needed to reach a palindrome.at n=25A015988
- Least k such that tan(k) > tan(a(n-1)), for n >= 1, where a(0) = 0.at n=40A024814
- [ exp(11/21)*n! ].at n=6A030845
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 62 ones.at n=9A031830
- Denominators of continued fraction convergents to sqrt(940).at n=9A042819
- Numbers k where cos(k) decreases monotonically to 0.at n=15A046957
- Numbers k where sin(k) increases monotonically to 1 (or cosec(k) decreases).at n=19A046959
- Smallest value of x such that M(x) = n, where M() is Mertens's function A002321.at n=32A051400
- Inverse Mertens function: smallest k such that |M(k)| = n, where M(x) is Mertens's function A002321.at n=32A051402
- An inverse to Mertens's function: smallest k >= 2 such that Mertens's function |M(k)| (see A002321) is equal to n.at n=33A060434
- Numbers k such that floor(tan(k)) > floor(tan(m)) for all m < k.at n=37A063537
- Numbers which need eight 'Reverse and Add' steps to reach a palindrome.at n=20A065213
- A113695(n-1) concatenated with A113695(n+1) divided by A113695(n).at n=4A113696
- Least semiprime s for which the Mertens function M(s) = n.at n=36A123173
- Number of ways to build a contiguous building with n LEGO blocks of size 1 X 8 on top of a fixed block of the same size.at n=1A123814
- a(n) = Least i in range [A165583(n),A165583(n+1)] for which abs(A165582(i)) gets the maximum value in that range.at n=33A165584
- a(n) = A000041(n) + n*A032741(n).at n=32A168015
- Numbers x such that 0 < |x^7 - y^4| < x^(17/4) for some number y.at n=6A173358