6723
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
- 3
Divisibility
- Divisor Count
- 10
- Divisor Sum
- 10164
- Proper Divisor Sum (Aliquot Sum)
- 3441
- 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
- 4428
- Möbius Function
- 0
- Radical
- 249
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 2
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
- 44
- 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
- a(n) = 4*n^2 - 1.at n=41A000466
- a(n) = solution to the postage stamp problem with 3 denominations and n stamps.at n=46A001208
- a(n) = (4*n+1)*(4*n+3).at n=20A001539
- Numbers k such that 57*2^k + 1 is prime.at n=22A002274
- Tetrahedral numbers written backwards.at n=26A004161
- a(n) = number of (s(0), s(1), ..., s(n)) such that every s(i) is an integer, s(0) = 0, |s(i) - s(i-1)| = 1 for i = 1,2,3; |s(i) - s(i-1)| <= 1 for i >= 4, s(n) = 1. Also a(n) = T(n,n-1), where T is the array defined in A026082.at n=7A026084
- a(n) = Sum_{j=0..2*i, i=0..n} A026584(i,j).at n=9A026599
- Composite numbers whose prime factors contain no digits other than 3 and 8.at n=13A036317
- The sequence e when b=[ 1,1,0,1,1,... ].at n=45A042955
- Numbers having three 0's in base 9.at n=25A043455
- a(n) = a(n-2) + a(n-3), with a(0) = 3, a(1) = 2, a(2) = 6.at n=28A046877
- a(n) = a(n-1) + a(m) for n >= 3, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 3.at n=40A050069
- Numbers n such that 55*2^n-1 is prime.at n=31A050553
- a(n) = A048141(3*n+2).at n=48A051060
- Trajectory of 3 under map n->7n-1 if n odd, n->n/2 if n even.at n=23A063871
- Numbers k such that sopf(k) = 2*sopf(k+1), where sopf(k) = A008472.at n=11A064112
- Numbers k such that sopf(k) = sopfr(k+1), where sopf(k) = A008472(k) and sopfr(k) = A001414(k).at n=18A064678
- Numbers k such that tau(k) - tau(k+1) = 1.at n=13A068208
- Quotient of LCM of prime(n+1)-1 and prime(n)-1 and GCD of the same two numbers.at n=37A083555
- Number of lattice points on or inside the rectangle formed by [1 <= x <= (q-1)/2] and [1 <= y <= (p-1)/2], where p = n-th prime, q = (n-1)-st prime.at n=36A087427