16745
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 23
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 21384
- Proper Divisor Sum (Aliquot Sum)
- 4639
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 12544
- Möbius Function
- -1
- Radical
- 16745
- 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
- 110
- 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
- Pseudoprimes to base 33.at n=39A020161
- Pseudoprimes to base 77.at n=42A020205
- Pseudoprimes to base 84.at n=40A020212
- a(n) = n*(29*n - 1)/2.at n=34A022286
- a(n) = Sum_{k=0..floor(n/2)} T(n,k), T given by A026780.at n=12A026788
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted the two central terms are both 13.at n=14A031601
- a(n) = n^4/2 - n^3 + 3*n^2/2 - n + 1 = (n^2 + 1)*(n^2 - 2*n + 2)/2.at n=14A058919
- For 1 < x, each c(i) is "multiply" (*) or "divide" (/); a(n) is number of choices for c(0),...,c(n-1) so that 1 c(0) x^1 c(1) x^2,.., c(n-1) x^n is an integer.at n=15A059529
- A060448 sorted and duplicates removed.at n=28A060636
- Integer part of log(n!)^(1 + log(n)).at n=10A062473
- Numbers that are sums of 2 or more consecutive squares in more than 1 way.at n=22A062681
- Triangle T(n,m) = sum_{k=m..n} A001263(k,m).at n=61A104711
- Least multiple of prime(n) ending in digits of n.at n=41A114012
- Numbers that are the sum of one or more consecutive squares in more than one way.at n=28A130052
- Positive numbers y such that y^2 is of the form x^2+(x+17)^2 with integer x.at n=13A155923
- a(n) = 6*a(n-1)-a(n-2) for n > 2; a(1) = 17, a(2) = 85.at n=4A156157
- Number of different fixed (possibly) disconnected tetrominoes bounded (not necessarily tightly) by an n X n square.at n=5A162674
- a(n) = prime(n)^3 mod (n^2 + prime(n)^2).at n=37A243769
- First differences of A024431.at n=23A247414
- Number of (6+2)X(n+2) 0..4 arrays with every consecutive three elements in every row and diagonal having exactly two distinct values, and in every column and antidiagonal not having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=8A252967