5691
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8704
- Proper Divisor Sum (Aliquot Sum)
- 3013
- 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
- 3240
- Möbius Function
- -1
- Radical
- 5691
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 173
- 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
- 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 50.at n=22A031548
- a(1) = 4; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=42A046254
- a(1) = 8; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=35A046258
- Number of distinct resistances that can be produced from a circuit of n equal resistors using only series and parallel combinations.at n=10A048211
- a(n) = Xpower(n,3).at n=23A048732
- Interprimes (A024675) which are of the form s*prime, s=21.at n=18A075296
- a(n) = A000094(n+4) - A006918(n).at n=27A084835
- (prime(n)*(prime(n+1)-1) + (prime(n)-1)*prime(n+1)) / 2.at n=19A099909
- Start with 1027 and repeatedly reverse the digits and add 16 to get the next term.at n=8A119455
- Number of square tiles in all tilings of a 3 X n board with 1 X 1 and L-shaped tiles (where the L-shaped tiles cover 3 squares).at n=4A127868
- a(n) is the largest path count within the (right-aligned Ferrers plots of the) partitions of n.at n=53A180682
- a(n) = 2*a(n-1)+3*a(n-2)+5^n for n>1, a(0)=-2, a(1)=1.at n=5A200859
- a(n) is the largest k in an n_nacci(k) sequence (Fibonacci(k) for n=2, tribonacci(k) for n=3, etc.) such that n_nacci(k) >= 2^(k-n-1).at n=10A202805
- Composite numbers which yield a prime whenever a 5 is inserted anywhere in them, excluding at the end.at n=47A216167
- One half of the radical (squarefree kernel) of the abc-triples (a=1, b(n) = A216323(n), c(n) = 1 + b(n)).at n=36A216324
- Numbers k such that 13*k+1 is a square.at n=41A219389
- Total number of parts in all partitions of n plus the sum of largest parts in all partitions of n plus the number of partitions of n plus n.at n=18A225610
- Number of ways of writing n as the sum of 7 triangular numbers.at n=26A226252
- 29-gonal numbers: a(n) = n*(27*n-25)/2.at n=21A255187
- a(1) = 6; for n > 1, a(n) = the least squarefree composite number whose sum of prime factors is prime and whose greatest prime factor is the sum of prime factors of a(n-1).at n=32A262081