16815
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
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 28800
- Proper Divisor Sum (Aliquot Sum)
- 11985
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 8352
- Möbius Function
- 1
- Radical
- 16815
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- 66
- 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
- Stirling numbers of the first kind: s(n+2, n).at n=18A000914
- Stirling numbers of first kind S1(20,n).at n=17A011530
- Numbers k such that sigma(k) = sigma(k+6).at n=35A015866
- Odd numbers to the right of the central elements of the (2,3)-Pascal triangle A029600.at n=50A029616
- Odd numbers to left of central elements of the (3,2)-Pascal triangle A029618.at n=51A029630
- Sums of distinct powers of 7.at n=35A033044
- Positive numbers having the same set of digits in base 2 and base 7.at n=29A037412
- Sums of 3 distinct powers of 7.at n=10A038482
- Digitally balanced numbers in base 4: equal numbers of 0's, 1's, ... 3's.at n=18A049355
- Sequence resulting from a sum of three repeated binomial(n+3,4) sequences.at n=35A093039
- Polar structured meta-anti-diamond numbers, the n-th number from a polar structured n-gonal anti-diamond number sequence.at n=14A100188
- Primitive elements of A119432.at n=36A119433
- Numbers of the form a^b + c^d where a, b, c and d are the first 4 primes.at n=8A168349
- Ordered Stirling numbers S1(n,k) >= 0.at n=25A193245
- Small rhombicosidodecahedron with faces of centered polygons.at n=7A193251
- Numbers whose sum of triangular divisors is also a divisor and greater than 1.at n=21A209311
- Numbers of the form 7^j + 8^k, for j and k >= 0.at n=26A226825
- Number of n X 3 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).at n=4A230179
- T(n,k)=Number of nXk 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).at n=25A230184
- Number of 5Xn 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).at n=2A230188