17690
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 33480
- Proper Divisor Sum (Aliquot Sum)
- 15790
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 6720
- Möbius Function
- 1
- Radical
- 17690
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 97
- 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
- yes
- Odd
- no
Appears in sequences
- Apply partial sum operator twice to Fibonacci numbers.at n=18A001924
- Fibonacci sequence beginning 0, 29.at n=15A022363
- a(0)=1, a(n) = Fibonacci(2n+4) - (2n+3).at n=9A027953
- Denominators of the first differences of 1/(n^2 + 1).at n=11A033466
- Solution to the Dancing School Problem with n girls and n+2 boys: f(n,2).at n=16A079921
- Indices of primes that are the sum of two Fibonacci numbers.at n=36A178971
- a(n) = Fibonacci(n+8) - Fibonacci(8).at n=14A180673
- Number of strictly increasing arrangements of 4 nonzero numbers in -(n+2)..(n+2) with sum zero.at n=42A188123
- Number of 1X9 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 1 zero-sum 9-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=8A192696
- Coefficient of x in the reduction by x^2->x+1 of the polynomial p(n,x) defined at Comments.at n=16A193045
- s(k)-s(j), where the pairs (k,j) are given by A205852 and A205853, and s(k) denotes the (k+1)-st Fibonacci number.at n=31A205854
- s(k)-s(j), where the pairs (k,j) are given by A205877 and A205878, and s(k) denotes the (k+1)-st Fibonacci number.at n=16A205879
- Numbers k that are the product of four distinct primes such that x^2+y^2 = k has integer solutions.at n=27A248712
- Numbers of the form m^2 + 1 that can be expressed in more than one way as j^2 + k^2 with j > k > 1.at n=23A299708
- Numbers of the form m^2 + 1 that can be expressed in more than one way as j^2 + k^2 with j > k > 1 and gcd(j,k) = 1.at n=10A300166
- a(n) = gcd(A330050(n), A330051(n)).at n=14A329421
- a(n) is the number of vertices formed by n-secting the angles of a heptagon.at n=41A335758
- Numbers k such that (Sum of totatives of k) == 1 (mod Sum of primes dividing k with multiplicity).at n=38A340299
- Number of cells in a regular 7-gon after n generations of mitosis.at n=22A349808
- Integers of the form k^2 + 1, where k >= 1, that are the product of two other integers of the form k^2 + 1, where k >= 1.at n=16A372496