8905
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 11592
- Proper Divisor Sum (Aliquot Sum)
- 2687
- 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
- 6528
- Möbius Function
- -1
- Radical
- 8905
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 96
- 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
- a(n) = prime(n)*(prime(n-1)-1)/2.at n=30A014302
- Pseudoprimes to base 41.at n=45A020169
- Pseudoprimes to base 96.at n=28A020224
- Strong pseudoprimes to base 37.at n=8A020263
- a(n) = (d(n)-r(n))/2, where d = A026043 and r is the periodic sequence with fundamental period (1,1,0,0).at n=34A026044
- a(n) = T(n,n-3), where T is the array in A026374.at n=24A026382
- a(n) = T(n,n-3), where T is the array in A026386.at n=24A026394
- Expansion of 1/((1-3x)(1-4x)(1-10x)(1-12x)).at n=3A028051
- Zero, together with positive numbers k such that prime(k) + k is a square.at n=31A064371
- Gregorian calendar years with Ascension Day in April.at n=38A084427
- Numbers n such that prime(n) + n is a perfect power.at n=36A107605
- Numbers k such that k * (k+1) is the concatenation of a number m with itself.at n=4A116285
- Values of hypotenuse of primitive Pythagorean triples which can have four different shapes (that is, four different sets of "legs").at n=29A159781
- a(n) = (prime(n))^2 - (nonprime(n))^2.at n=25A161757
- Where records occur in A169784.at n=37A175437
- Fundamental discriminants d uniquely characterizing all complex biquadratic fields Q(sqrt(-3),sqrt(d)) which have 3-class group of type (3,3) and second 3-class group isomorphic to SmallGroup(729,95).at n=1A250239
- Numbers k of the form a - b + c, such that k^3 equals the decimal concatenation a//b//c and numbers k, b, and c have the same number of digits.at n=17A259379
- Numbers k of the form abs(a - b + c - d) such that k^4 equals the concatenation of a//b//c//d and numbers k,b,c,d have the same number of digits.at n=20A260193
- Numbers n that are the product of three distinct odd primes and x^2 + y^2 = n has integer solutions.at n=28A264498
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 20", based on the 5-celled von Neumann neighborhood.at n=38A269713