8519
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9744
- Proper Divisor Sum (Aliquot Sum)
- 1225
- 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
- 7296
- Möbius Function
- 1
- Radical
- 8519
- 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
- 158
- 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
- Number of partitions of floor(7n/2)-1 into n nonnegative integers each no greater than 7.at n=17A001980
- Discriminants of quintic fields with 2 complex conjugates (negated).at n=7A023684
- a(n) is the sum of squares of the first n positive integers congruent to 2 mod 3.at n=13A024394
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = A001950 (upper Wythoff sequence).at n=23A024689
- a(n) = position of n^3 + (n+1)^3 + (n+2)^3 in A024975.at n=29A024980
- s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n-k+1), where k = [ n/2 ], s = A001950 (upper Wythoff sequence).at n=22A025122
- 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 91.at n=18A031589
- a(n) = a(n-1) + a(round(2*(n-1)/3)) + a(round((n-1)/3)) with a(1)=a(2)=1.at n=33A033499
- Number of partitions of n into parts 3k or 3k+1.at n=47A035360
- Semiprimes whose prime factors, when concatenated, yield a palindrome.at n=46A046451
- Numbers k such that A055079(k) = 2^k.at n=24A057838
- Hard numbers: a(n) = smallest positive number m with f(m) = n, where f(m) is the smallest number of digits that are needed to construct m using only 1's, 2's and any number of +, -, *, ^ signs, not allowing concatenation of the digits.at n=12A060274
- Numbers k > 1 such that, in base 4, k and k^2 contain the same digits in the same proportion.at n=26A061658
- Numbers k such that k!! + 2^3 is prime.at n=23A076188
- a(1) = 10; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=45A111524
- Least semiprime s for which the Mertens function M(s) = n.at n=37A123173
- a(1) = 1; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that any four consecutive digits in the sequence sum up to a prime.at n=42A152604
- a(n) = Least i in range [A165583(n),A165583(n+1)] for which abs(A165582(i)) gets the maximum value in that range.at n=34A165584
- Partial sums of Pillai primes (A063980).at n=34A172034
- Triangle T(n,k) = |Re|+|Im| where Re+i*Im is the complex coefficient of [x^k] of the series (1-x)^(n+1) * Sum_{k>=0} ((1+i)*k+i)^n *x^k and i the imaginary unit, row n and column k.at n=30A179086