6405
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 11904
- Proper Divisor Sum (Aliquot Sum)
- 5499
- 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
- 2880
- Möbius Function
- 1
- Radical
- 6405
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 62
- 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
- Number of sublattices of index n in generic 3-dimensional lattice.at n=51A001001
- Number of simple arrangements of pseudolines in the projective plane with an oriented marked cell; number of oriented abstract order types of n points (distinguishing mirror-symmetric copies).at n=7A006246
- Number of distributive lattices; also number of paths with n turns when light is reflected from 6 glass plates.at n=6A006359
- a(n) = floor(n*(n+2)*(2*n-1)/8).at n=28A007518
- Number of set-like molecular species of degree n.at n=19A007649
- Numbers k that divide s(k), where s(1)=1, s(j)=15*s(j-1)+j.at n=34A014865
- Pseudoprimes to base 62.at n=42A020190
- a(n) = n*(29*n + 1)/2.at n=21A022287
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 32.at n=4A031710
- Shifts left and changes sign under Weigh transform.at n=21A038074
- Squarefree odd numbers with exactly 4 distinct prime factors.at n=35A046390
- Table read by ascending antidiagonals: T(n, m) giving total degree of n-th-order elementary symmetric polynomials in m variables.at n=71A050446
- Table T(n,m) giving total degree of n-th-order elementary symmetric polynomials in m variables, -1 <= n, 1 <= m, transposed and read by upward antidiagonals.at n=72A050447
- Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 6 skipped primes.at n=37A050773
- Rounded total surface area of a regular octahedron with edge length n.at n=43A071396
- Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=6.at n=25A076672
- Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=7.at n=21A076673
- Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=10.at n=21A076675
- Smallest a(n)>a(n-1) such that a(n)^2+a(n-1)^2 is a perfect square, a(1)=11.at n=19A076676
- 2-nadirs of phi: numbers k such that phi(k-2) > phi(k-1) > phi(k) < phi(k+1) < phi(k+2).at n=30A076773