16781
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
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 17052
- Proper Divisor Sum (Aliquot Sum)
- 271
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 16512
- Möbius Function
- 1
- Radical
- 16781
- 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
- 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
- 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
- Numerator of fraction equal to the continued fraction [ 3, 1, 4, 1, 5... ] (first n digits of Pi).at n=7A036253
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 19.at n=8A051984
- Numbers k such that 7*10^k + 3*R_k is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=18A056720
- Number of (n+4) X 11 0..1 matrices with each 5 X 5 subblock idempotent.at n=12A224689
- Number of partitions of n not having depth 1; see Comments.at n=40A238003
- Numbers k such that 7*10^k + 79 is prime.at n=25A282250
- Composite hypotenuses of primitive Pythagorean triangles (A120961) that are not circumdiameters of non-Pythagorean primitive Heronian triangles (A285579).at n=20A329148
- Primitive terms of A338890.at n=30A338892
- Number of polycubes of size n and symmetry class F.at n=12A376970