5781
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
- 8064
- Proper Divisor Sum (Aliquot Sum)
- 2283
- 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
- 3680
- Möbius Function
- -1
- Radical
- 5781
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 49
- 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
- 9-gonal (or enneagonal or nonagonal) numbers: a(n) = n*(7*n-5)/2.at n=41A001106
- Centered tetrahedral numbers.at n=20A005894
- Expansion of tan(tan(sinh(x))) (odd powers only).at n=3A009691
- Pseudoprimes to base 46.at n=46A020174
- Expansion of (1-x^8)*(1+x^5)/(1-x^2)^5.at n=40A027635
- Expansion of (1-x^8)*(1+x^5)/(1-x^2)^5.at n=45A027635
- Odd 9-gonal (or enneagonal) numbers.at n=20A028991
- Expansion of Molien series for 4-D extraspecial group 2^{1+2*2}.at n=40A030533
- a(n) = (2*n+1)*(7*n+1).at n=20A033572
- Numerators of continued fraction convergents to sqrt(590).at n=5A042130
- Table T(n,k) = Sum_{i=0..2n} (C(2n,i) mod 2)*F(i+k) = Sum_{i=0..n} (C(n,i) mod 2)*F(2i+k).at n=56A050609
- Sum_{i=0..n} (C(n,i) mod 2)*Fibonacci(2i+1) = FL(n+1)Product(L(2^i)^bit(n,i),i=0..).at n=9A050611
- Numbers k such that 277*2^k-1 is prime.at n=12A050897
- Number of independent sets of vertices in graph K_4 X C_n (n > 2).at n=6A051929
- Table M(n,b) (columns: n >= 1, rows: b >= 0) gives the number of site swap juggling patterns with exact period n, using exactly b balls, where cyclic shifts are not counted as distinct.at n=68A065177
- Number of site swap patterns with 2 balls and exact period n.at n=9A065178
- Positive integers k such that 24*k^2 - 23 is a square.at n=8A074061
- a(n) = Lucas(4*n+2) + 3, or Lucas(2*n)*Lucas(2*n+2).at n=4A081077
- C(2*n+4,4)-C(2*n,4).at n=10A085474
- Numbers n such that 8*10^n + 5*R_n - 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=5A103083