16806
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
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 33624
- Proper Divisor Sum (Aliquot Sum)
- 16818
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 5600
- Möbius Function
- -1
- Radical
- 16806
- 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
- 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
- yes
- Odd
- no
Appears in sequences
- Pseudoprimes to base 7.at n=25A005938
- a(n) is the smallest positive number such that the sum of A001032(n) consecutive squares starting with a(n)^2 is a square.at n=49A007475
- a(n) = 7^n-1.at n=5A024075
- Dirichlet convolution of phi(n) with Catalan numbers.at n=10A034766
- Numbers that are repdigits in base 7.at n=30A048332
- Consider the Diophantine equation x^3 + y^3 = z^3 - 1 (x < y < z) or 'Fermat near misses'. The values of z (see A050787) are arranged in monotonically increasing order. Sequence gives values of y.at n=18A050789
- Numbers k such that k^6 == 1 (mod 7^5).at n=5A056103
- Jordan function J_5(n).at n=6A059378
- Triangle read by rows: T(n,k) = (n+1,k)-th element of (M^7-M)/6, where M is the infinite lower Pascal's triangle matrix, 1<=k<=n.at n=16A096041
- Numbers whose set of base 7 digits is {0,6}.at n=31A097253
- a(n) is the smallest nonprime k such that tau(k + n) = tau(k) + n , where tau(n) is the number of divisors of n (A000005).at n=41A099642
- Period of the Lucas 5-step sequence A074048 mod n.at n=27A106297
- Period of the Fibonacci 5-step sequence A001591 mod n.at n=13A106303
- Least even pseudoprime > p to base p, where p = prime(n).at n=3A108162
- Even pseudoprimes to base 7.at n=1A130434
- Numbers expressible as the difference of two nonnegative fifth powers.at n=28A152045
- Difference of two positive 5th powers.at n=22A181124
- Numbers of the form i*7^j-1 (i=1..6, j >= 0).at n=30A181303
- Monotonic ordering of nonnegative differences 7^i-2^j, for 40>=i>=0, j>=0.at n=45A192119
- Monotonic ordering of nonnegative differences 7^i-3^j, for 40>= i>=0, j>=0.at n=29A192154