16801
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 17172
- Proper Divisor Sum (Aliquot Sum)
- 371
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 16432
- Möbius Function
- 1
- Radical
- 16801
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- yes
- 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
- 159
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- Number of intersections of diagonals in the interior of a regular n-gon.at n=29A006561
- Numbers k such that the continued fraction for sqrt(k) has period 71.at n=9A020410
- Numbers whose base-7 representation contains exactly four 6's.at n=25A043420
- Number of fixed points in range [A014137(n-1)..A014138(n-1)] of permutation A089851/A089853.at n=11A089848
- Semiprimes in A056106.at n=27A113524
- Pentagonal numbers (A000326) whose digit reversal is a prime.at n=17A115707
- a(n) = 7*n^2 + 14*n + 1.at n=48A131878
- Pentagonal numbers that are the sum of a nonzero pentagonal number and a nonzero square in at least one way.at n=37A134938
- G.f. satisfies: A(x) = 1 + x*A(x)^3/A(-x)^2.at n=7A143562
- Number of planar triangular n X n X n nonnegative integer grids with mirror symmetry about one altitude with every similarly oriented 5 X 5 X 5 subtriangle summing to 9.at n=3A154075
- a(n) = 42*n^2 + 1.at n=20A158604
- a(n) = 7^n-6.at n=4A164783
- Array T(n, k) = k^(n-1) + (k-1)*cos(n*Pi/2), read by antidiagonals.at n=60A174006
- Square array T(n,k) = k^n - k + 1 read by antidiagonals.at n=61A193871
- Last occurrence of n partitions in A204814.at n=24A205301
- Number of 2 X 2 matrices having all terms in {1,...,n} and even determinant.at n=12A211064
- Semiprimes of the form n*(3*n-1)/2.at n=17A245365
- a(n) = n^5-n+1.at n=7A272162
- Semiprimes of the form p(6p - 1).at n=10A330409
- a(n) = Sum_{1 <= x_1, x_2, x_3, x_4 <= n} n/gcd(x_1, x_2, x_3, x_4, n).at n=6A372961