6639
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8856
- Proper Divisor Sum (Aliquot Sum)
- 2217
- 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
- 4424
- Möbius Function
- 1
- Radical
- 6639
- Omega Function (Ω)
- 2
- 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
- 75
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- From a counter moving problem.at n=16A004138
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 27.at n=31A031525
- Number of partitions of 5n such that cn(1,5) = cn(4,5) < cn(0,5) < cn(2,5) = cn(3,5).at n=12A036894
- Number of primes between n*100000 and (n+1)*100000.at n=33A038825
- Honaker's triangle problem: form a triangle with base of length n, all entries different, all row sums equal; a(n) gives minimal row sum.at n=34A047837
- a(n) = max_{r=1..n-1} ceiling(t(t(n)-t(r-1))/(n-r+1)), where t() = triangular numbers A000217.at n=34A047873
- Numbers k such that 10*13^k + 1 is prime.at n=16A057464
- a(0)=1, a(n) is the smallest integer > a(n-1) such that the largest element in the simple continued fraction for S(n)= 1/a(0)+1/a(1)+1/a(2)+...+1/a(n) equals 2n.at n=42A070898
- Sum of the primes in ordered 3 X 3 prime squares.at n=14A105089
- Numbers k such that k divides Sum_{j=1..k} j^j = A001923(k).at n=9A128981
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 0), (0, 1, 0), (1, -1, -1), (1, 0, 0)}.at n=8A149911
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (0, -1, 1), (0, 1, -1), (1, 0, 0), (1, 0, 1)}.at n=7A150405
- First differences of the dying rabbits sequence A000044.at n=21A191869
- Number of odd entries in the character table of the symmetric group S_n.at n=14A274691
- Numbers k such that prime(k) divides primorial(j) + 1 for exactly two integers j.at n=43A279099
- Solution of the complementary equation a(n) = a(n-1) + a(n-2) + b(n-1) + n, where a(0) = 1, a(1) = 2, b(0) = 3, and (a(n)) and (b(n)) are increasing complementary sequences.at n=14A294546
- Partial sums of A298014.at n=47A298017
- Numbers k such that k and k+1 are terms of A279767.at n=39A300059
- a(n) is the smallest k such that A307092(k) = n.at n=20A307074
- Sum of the fourth largest parts in the partitions of n into 8 parts.at n=36A308995