7805
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 10752
- Proper Divisor Sum (Aliquot Sum)
- 2947
- 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
- 5328
- Möbius Function
- -1
- Radical
- 7805
- Omega Function (Ω)
- 3
- 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
- 176
- 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
- Maximal number of pieces obtained by slicing a torus (or a bagel) with n cuts: (n^3 + 3*n^2 + 8*n)/6 (n > 0).at n=35A003600
- Expansion of (1-x^5) / (1-x)^5.at n=21A008487
- a(0) = 1, a(n) = 27*n^2 + 2 for n>0.at n=17A010017
- Number of trivalent connected simple graphs with 2*n nodes and girth at least 4.at n=9A014371
- Integer part of ((4th elementary symmetric function of 2,3,...,n+4)/(2nd elementary symmetric function of 2,3,...,n+4)).at n=21A024181
- Values of Newton-Gregory forward interpolating polynomial (1/3)*(2*n-7)*(2*n^2-11*n+18).at n=21A030434
- Values of Newton-Gregory forward interpolating polynomial (1/3)*(2*n - 3)*(2*n^2 - 3*n + 4).at n=19A030441
- Number of perfect connected undirected simple graphs on n nodes.at n=7A052433
- Sums of terms of groups in A075621.at n=24A075625
- Number of partitions of n such that largest part k occurs at least floor(k/2) times.at n=52A118083
- Nearest integer to 1/frac(Pi^A137994(n)), where frac(x) = x - floor(x).at n=9A137995
- Binomial transform of [1, 4, 6, 4, 1, 1, -1, 1, -1, 1, ...].at n=17A140227
- Number of n X 3 binary arrays with all 1s connected, a path of 1s from upper left corner to lower right corner, and no 1 having more than two 1s adjacent.at n=10A163686
- Smallest a(n) such that the prime factorization of a(n)! contains at least one factor to each exponent between 1 and n.at n=35A177442
- Inverse of coefficient array of orthogonal polynomials P(n,x)=(x-n)*P(n-1,x)-(2n-3)*P(n-2,x), P(0,x)=1,P(1,x)=x-1.at n=51A178125
- Number of strings of numbers x(i=1..5) in 0..n with sum i^4*x(i) equal to 625*n.at n=45A184351
- Irregular triangle C(n,g) counting connected trivalent simple graphs on 2n vertices with girth at least g.at n=20A185131
- Triangle of coefficients of polynomials v(n,x) jointly generated with A210866; see the Formula section.at n=41A210867
- a(n) = n*(13*n - 9)/2.at n=35A226488
- Positions of peak values in A232221.at n=29A232359