17823
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 25648
- Proper Divisor Sum (Aliquot Sum)
- 7825
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10944
- Möbius Function
- -1
- Radical
- 17823
- 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
- 172
- 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
- Half the number of n X 5 binary arrays with no element unequal to a strict majority of its king-move neighbors.at n=11A183389
- Inverse of Riordan array ((1-x)(1-x^2)(1-x^3)/(1-x^6), x(1-x)(1-x^2)(1-x^3)/(1-x^6)).at n=47A185967
- a(n) gives the position of -n in the sequence (or tree) S generated in order by these rules: 0 is in S; if x is in S then x + 1 is in S; if nonzero x is in S then 1/x is in S; if x is in S, then i*x is in S; where duplicates are deleted as they occur.at n=11A233695
- Positions of integers in the sequence (or tree) S generated in order by these rules: 0 is in S; if x is in S then x + 1 is in S; if nonzero x is in S then 1/x is in S; if x is in S, then i*x is in S; where duplicates are deleted as they occur.at n=26A233696
- Numbers n such that n = concatenate(a, b) and sigma(a) + sigma(b) = sigma(n) - n.at n=8A239562
- 26-gonal numbers: a(n) = n*(12*n-11).at n=39A255185
- Least integer k such that the n-th prime of form m^2+1 divides the composite number k^2+1.at n=25A255675
- Number of integers in n-th generation of tree T(-3/2) defined in Comments.at n=26A274154
- Positive integers m such that 2*m^2 - 1 = x^4 + y^4 for some nonnegative integers x and y with |x - y| > 1.at n=5A343913
- Number of ways that n can be expressed as a sum of consecutive integers from 0 up to at most n, where any of the terms in the sum can be negated, and the partial sum from 0 is always between 0 and n inclusive.at n=57A364721
- Indices k such that A377091(k) is immediately followed by A377091(k+1) = -A377091(k).at n=53A379802
- Number of connected components of n faces of the truncated dodecahedron up to the 120 rotations and reflections of the truncated dodecahedron.at n=9A384108