11581
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 11932
- Proper Divisor Sum (Aliquot Sum)
- 351
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11232
- Möbius Function
- 1
- Radical
- 11581
- 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
- 55
- 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
- Pseudoprimes to base 29.at n=47A020157
- Strong pseudoprimes to base 29.at n=11A020255
- Numbers k such that the continued fraction for sqrt(k) has period 77.at n=14A020416
- a(n) = dot_product(n,n-1,...2,1)*(5,6,...,n,1,2,3,4).at n=32A026060
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 21.at n=17A051986
- Counterbalanced numbers: Composite numbers k such that phi(k)/(sigma(k)-k) is an integer.at n=16A055940
- McKay-Thompson series of class 17A for the Monster simple group.at n=18A058530
- Number of permutations satisfying i-3<=p(i)<=i+4, i=1..n.at n=8A072854
- Indices of primes in sequence defined by A(0) = 49, A(n) = 10*A(n-1) - 71 for n > 0.at n=6A101718
- a(n) = floor(((1+sqrt(3))/2)^n).at n=29A125895
- McKay-Thompson series of class 17A for the Monster group with a(0) = 2.at n=18A152944
- Integers k such that (k^2 + (k+1)^2) has no square proper substring.at n=60A238903
- Semiprimes generated by the polynomial 2 * n^2 + 29.at n=14A241554
- Number of (n+2)X(2+2) nonnegative integer arrays with all values the knight distance from the upper left minus as much as 3, with successive minimum path knight move differences either 0 or +1, and any unreachable value zero.at n=2A253336
- Number of (n+2)X(3+2) nonnegative integer arrays with all values the knight distance from the upper left minus as much as 3, with successive minimum path knight move differences either 0 or +1, and any unreachable value zero.at n=1A253337
- T(n,k)=Number of (n+2)X(k+2) nonnegative integer arrays with all values the knight distance from the upper left minus as much as 3, with successive minimum path knight move differences either 0 or +1, and any unreachable value zero.at n=7A253342
- T(n,k)=Number of (n+2)X(k+2) nonnegative integer arrays with all values the knight distance from the upper left minus as much as 3, with successive minimum path knight move differences either 0 or +1, and any unreachable value zero.at n=8A253342
- Numbers k such that k^2 + 1 = p*q*r*s where p,q,r,s are distinct primes and the sum p+q+r+s is a perfect square.at n=41A261530
- Triangle read by rows: T(n,m) = Sum_{i=0..m} Stirling2(m+1,i+1)*(-1)^(m-i)*i^(n-m)*i!, for n >= 2, m = 1..n-1.at n=31A272644
- Triangle read by rows: T(n,m) = Sum_{i=0..m} Stirling2(m+1,i+1)*(-1)^(m-i)*i^(n-m)*i!, for n >= 2, m = 1..n-1.at n=32A272644