8175
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
- 12
- Divisor Sum
- 13640
- Proper Divisor Sum (Aliquot Sum)
- 5465
- 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
- 4320
- Möbius Function
- 0
- Radical
- 1635
- Omega Function (Ω)
- 4
- 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
- 145
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Generalized Stirling numbers, [n+8,8]_5.at n=3A001723
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (composite numbers), t = (primes).at n=22A024604
- Lucky numbers with size of gaps equal to 16 (lower terms).at n=24A031898
- Sums of 12 distinct powers of 2.at n=8A038463
- Shifts left under transform T where Ta is product of Partition Triangle A008284 with a.at n=12A039808
- Number of 3 x n binary matrices without unit columns up to row and column permutations.at n=29A057524
- Numbers n such that zero is never reached by iterating the mapping k -> abs(reverse(lpd(k))-reverse(gpf(k))). lpd(k) is the largest proper divisor and gpf(k) is the largest prime factor of k.at n=21A076425
- Numbers n such that ((n-1)^2+1)/2 and n^2+1 and ((n+1)^2+1)/2 are prime if n is even or (n-1)^2+1 and (n^2+1)/2 and (n+1)^2+1 are prime if n is odd.at n=40A082612
- Number of different configurations of cycles (loops) in graphs containing directed and undirected links.at n=8A117747
- Number of numerical semigroups with Frobenius number n; that is, numerical semigroups for which the largest integer not belonging to them is n.at n=25A124506
- Numbers of length n binary words with fewer than 9 0-digits between any pair of consecutive 1-digits.at n=13A145117
- 3 times 11-gonal (or hendecagonal) numbers: a(n) = 3*n*(9*n-7)/2.at n=25A153783
- Integers of the form 4n+3 for which Sum_{i=1..u} J(i,4n+3) obtains value zero exactly 9 times, when u ranges from 1 to (4n+3). Here J(i,k) is the Jacobi symbol.at n=25A166059
- Fixed points of the mapping f(x) = (x + 2^x) mod (17 + x).at n=8A166118
- The ED3 array read by antidiagonals.at n=32A167572
- The fourth row of the ED3 array A167572.at n=4A167574
- Numbers y such that 19*y^2 + 81 is a square.at n=8A167709
- Subsequence of A167709 whose indices are congruent to 3 mod 5, i.e., a(n) = A167709(5*n+3).at n=1A167824
- Augmentation of the triangle A193605. See Comments.at n=31A193606
- Least number m such that phi(m-6n) = phi(m) = phi(m+6n) and m is not divisible by n.at n=8A217068