6745
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8640
- Proper Divisor Sum (Aliquot Sum)
- 1895
- 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
- 5040
- Möbius Function
- -1
- Radical
- 6745
- 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
- 75
- 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
- a(n) is the solution to the postage stamp problem with 4 denominations and n stamps.at n=24A001209
- a(n) = (3*n - 1)*(4*n - 1).at n=24A033578
- Numbers whose base-4 representation contains exactly four 1's and three 2's.at n=17A045108
- Odd composite numbers divisible by the sum of their prime factors (counted with multiplicity).at n=24A046347
- a(n) = Fibonacci(n) - n.at n=20A065220
- Numbers k such that phi(5k+1) = sigma(k).at n=1A067226
- Number of ordered triples (a, b, c) with gcd(a, b, c) = 1 and 1 <= {a, b, c} <= n.at n=19A071778
- a(n) = Sum_{i=n+1..2n} prime(i) - Sum_{i=1..n} prime(i).at n=35A077354
- Greedy frac multiples of 1/Pi: a(1)=1, Sum_{n>0} frac(a(n)*x) = 1 at x=1/Pi, where "frac(y)" denotes the fractional part of y.at n=25A080142
- Perrin sequence of order 5.at n=57A087935
- Triangle read by rows: T(n,k) is the number of deco polyominoes of height n and such that the sum of the bottom levels of all columns is k (n>=1, k>=0; informally, the number of the "missing" cells in the right bottom corner of the polyomino). A deco polyomino is a directed column-convex polyomino in which the height, measured along the diagonal, is attained only in the last column.at n=51A122104
- Number of ways, counted up to symmetry, to build a contiguous building with n LEGO blocks of size 1 X 4 which is flat, i.e., with all blocks in parallel position and symmetric after a rotation by 180 degrees.at n=9A123781
- A106486-encodings of combinatorial games equivalent to game {0|1}.at n=31A125997
- Composite numbers that are products of distinct primes and divisible by the sum of those primes.at n=23A131647
- Numbers n where |sinc(n)| decreases monotonically to 0 (where sinc(x)=sin(x)/x).at n=44A131975
- Prime numbers concatenated with 45.at n=18A137521
- Numbers k = p*q*r (p, q, r prime) congruent to 0 mod p+q+r.at n=18A160394
- Coefficients in the expansion of C^4/B^5, in Watson's notation of page 118.at n=8A160528
- a(1) = 1, and for each k >=2, a(k) is the smallest number n such that n/sin(n) > a(k)/sin(a(k)), so that a(1)/sin(a(1)) > a(2)/sin(a(2)) > ... > a(k)/sin(a(k)) > ...at n=23A172445
- Number of solutions to the Diophantine equation x1*x2 + x2*x3 + x3*x4 + x4*x5 + x5*x6 = n, with all xi >= 1.at n=46A191832