5805
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 10560
- Proper Divisor Sum (Aliquot Sum)
- 4755
- 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
- 3024
- Möbius Function
- 0
- Radical
- 645
- Omega Function (Ω)
- 5
- 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
- 142
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Number of permutations of length n by rises.at n=2A001280
- Irregular triangle read by rows: T(n,k) (n>=1, 0 <= k <= floor(n/2)) = number of permutations of 1..n with exactly floor(n/2) - k runs of consecutive pairs up.at n=30A010029
- Expansion of Product_{m>=1} (1 - m*q^m)^6.at n=14A022666
- Expansion of 1/((1-2x)(1-4x)(1-8x)(1-11x)).at n=3A025978
- Gaps of 2 in sequence A038593 (upper terms).at n=10A038644
- Numbers that are divisible by 5 and are the difference between two (different positive) cubes in at least one way.at n=27A038853
- Numbers ending with '5' that are the difference of two positive cubes.at n=19A038860
- Take n points in general position in the plane; draw all the (infinite) straight lines joining them; sequence gives number of connected regions formed.at n=16A055503
- 9 times octagonal numbers: a(n) = 9*n*(3*n-2).at n=15A064201
- a(n) = 3*n^2 + 6*n.at n=43A067725
- Unicode codes for the lunation runes, used in certain medieval Scandinavian perpetual calendar staves as golden numbers 1-19.at n=3A098476
- Triangle, read by rows, where g.f. of row n equals the product of (1-x)^n and the g.f. of the coordination sequence for root lattice B_n, for n >= 0.at n=57A109001
- a(n) is decimal value of s(n), as defined in A096055, if s(n) concatenated is a binary number.at n=3A112396
- Records in A110566 (lcm{1,2,...,n}/denominator of harmonic number H(n)).at n=9A112810
- Terms of A110566 grouped.at n=56A112811
- Number of ways to build a contiguous building with n LEGO blocks of size 5 X 5 on top of a fixed block of the same size so that the building is symmetric after a rotation by 180 degrees.at n=4A123848
- a(n) = (n-1)*(n+2)*(2*n+11)/2.at n=15A130862
- Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k maximal strings of increasing consecutive integers (0<=k<=floor(n/2)).at n=34A136123
- a(n) = n*(8*n-1).at n=27A139274
- Coefficients of polynomial P(n) by rows, with P(n) = (x+1)^n + 2^(n-3)*((x+1)^n - x^n - 1) for n > 0 and P(0) = 1.at n=57A146769