8639
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8856
- Proper Divisor Sum (Aliquot Sum)
- 217
- 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
- 8424
- Möbius Function
- 1
- Radical
- 8639
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 109
- 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
- "DFK" (bracelet, size, unlabeled) transform of 2,1,1,1...at n=31A032215
- Partial sums of primes congruent to 1 mod 6.at n=40A038349
- Partial sums of primes congruent to 5 mod 6.at n=42A038361
- Denominators of continued fraction convergents to sqrt(47).at n=8A041081
- Least inverse of A056796.at n=20A056817
- The least number k = a(n) > a(n-1) for which k!/(k+1)^m for increasing m's.at n=41A061769
- a(n) is the smallest number not already used such that a(n)*a(n-1)*a(n-2) + 1 is a square, with a(1)=1 and a(2)=2.at n=30A064691
- Nonprime numbers n such that q=phi(n)/(sigma(n)-n-1) is an integer and n is not a prime square.at n=44A070161
- a(n) = A006046(A077465(n)).at n=8A077466
- Semiprimes n such that 3*n + 4 is a square.at n=19A112666
- 3n^3 + 2n^2 + n + 1.at n=14A130884
- Composite terms in A143578.at n=43A142591
- a(n) = 288*n - 1.at n=29A157997
- a(n) = 576*n - 1.at n=14A158372
- a(n) = 60*n^2 - 1.at n=11A158670
- Triangle read by rows: T(n,k) is the number of Dyck paths with no UUU's and no DDD's, of semilength n and having k UUDUDD's starting at level 0 (0 <= k <= floor(n/3); U=(1,1), D=(1,-1)).at n=35A166295
- Number of Dyck paths of semilength n with no UUU's and no DDD's and having no UUDUDD's starting at level 0 (U=(1,1), D=(1,-1)).at n=13A166296
- Number of 1X4 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 1 zero-sum 4-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=33A192691
- a(n) = 5*12^n - 1.at n=3A199107
- Number of compositions of n such that the number of parts and the smallest part are not coprime.at n=22A199889