17765
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 25920
- Proper Divisor Sum (Aliquot Sum)
- 8155
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11520
- Möbius Function
- 1
- Radical
- 17765
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- 185
- 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
- Geometric mean of phi(n) and sigma(n) is an integer, n odd.at n=31A015705
- a(n) = (2*n+1) * (4*n-1).at n=47A033566
- Number of stars of visual magnitude n.at n=8A072171
- Expansion of (5 - 9*x + 6*x^2)/(1-x)^4.at n=37A080957
- Denominator of 2*Sum(C(n,w)/(2*w+1),w=0..n/2-1)+C(n,n/2)/(n+1) if n is even, or of 2*Sum(C(n,w)/(2*w+1),w=0..(n-1)/2) if n is odd.at n=29A085569
- Numbers k such that 10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=26A102940
- Denominator of f(n) := Product_{i=1..n} sigma(i)/i.at n=18A111934
- 1 + Sum[ Prime[k]^(n-1), {k,1,n}].at n=4A120492
- Numbers k such that k and k+1 have 4 distinct prime factors.at n=19A140078
- Triangle read by rows: coefficients of the alternating factorial polynomial (x+1)(x-2)(x+3)(x-4)...(x+n*(-1)^(n-1)).at n=49A140956
- 5 times heptagonal numbers: a(n) = 5*n*(5*n-3)/2.at n=38A153785
- Numbers n such that sigma(n)/phi(n) = 9/4.at n=4A164646
- Positions of zeros in A165597.at n=20A165598
- Number of base 3 lunar primes of length n.at n=9A191366
- a(2) = 1, then (p-1)*(p-4)/2, with p = prime(n), n > 2.at n=41A200050
- a(n) is the number m such that f(sqrt(n)) is in the field Q(sqrt(m)), where f(x) is defined from the continued fraction x = [c(0), c(1), ... ] as [c(0) + 1, c(1) + 1, ...].at n=20A229957
- Number of length 4+1 0..n arrays with the sum of adjacent differences multiplied by some arrangement of +-1 equal to zero.at n=7A250169
- Numbers k such that (41*10^k + 49)/9 is prime.at n=23A254441
- Number of (n+2) X (6+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 3 and no row sum 1 and no column sum 1.at n=19A257445
- Numbers k such that k and k+1 each have at least 4 distinct prime factors.at n=19A321504