9165
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 16128
- Proper Divisor Sum (Aliquot Sum)
- 6963
- 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
- 4416
- Möbius Function
- 1
- Radical
- 9165
- 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
- 153
- 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
- Expansion of g.f. 1/((1 - 2*x)*(1 - 5*x)*(1 - 7*x)).at n=4A016296
- a(n) = least m such that if r and s in {1/2, 1/5, 1/8, ..., 1/(3n-1)} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.at n=42A024837
- (d(n)-r(n))/2, where d = A008778 and r is the periodic sequence with fundamental period (1,1,0,1).at n=44A026052
- Second pentagonal numbers with even index: a(n) = n*(6*n+1).at n=39A049453
- 23-gonal numbers: a(n) = n(21n-19)/2.at n=30A051875
- Areas of a sequence of right-angled figures described below.at n=16A058195
- Smallest number a(n)>a(n-1) such that T(a(n-1))+T(a(n))=T(m) for some m, a(1)=3; T(i) are the triangular numbers.at n=24A072522
- Diagonal sums of number array A082046.at n=12A082047
- Positions at which the sum of the digits of e up to that point equals the sum of the digits of Pi up to that point.at n=18A131660
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, -1), (-1, 1, 1), (0, -1, -1), (1, 1, 1)}.at n=8A149515
- Odd squarefree numbers n such that the cyclotomic polynomial Phi(n,x) has height 4.at n=41A152942
- a(n) = (prime(n))^2 - (nonprime(n))^2.at n=26A161757
- a(n) = a(n-1) * (11*a(n-1) - a(n-2)) / (a(n-1) + 4*a(n-2)), with a(0) = a(1) = 1.at n=7A172511
- a(n) = largest number k such that k and k * n taken together have distinct digits, or 0 if no such k exists.at n=37A173780
- Number of partitions of n having no parts with multiplicity 6.at n=33A184641
- Least odd k such that k*2^(2^n)+1 is prime.at n=13A187088
- Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2+x^2+y^2>=2n.at n=21A211645
- Smallest value of k such that Sum_{j=1..k} arctan(1/j) > n*Pi/2.at n=6A230126
- Products p*q*r*s of distinct primes for which (p*q*r*s + 1)/2 is prime.at n=14A234501
- Numbers n such that A062234(n) = A062234(n+1) = A062234(n+2).at n=38A258449