6643
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8288
- Proper Divisor Sum (Aliquot Sum)
- 1645
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 5184
- Möbius Function
- -1
- Radical
- 6643
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 106
- 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
- Numbers k such that (1,k) is "good".at n=39A000696
- sigma_4(n): sum of 4th powers of divisors of n.at n=8A001159
- Number of weighted voting procedures.at n=10A005254
- Number of Barlow packings with group P63mc that repeat after 2n layers.at n=13A011948
- Numerator of sum of -4th powers of divisors of n.at n=8A017671
- Fermat pseudoprimes to base 4.at n=36A020136
- Pseudoprimes to base 9.at n=42A020138
- Pseudoprimes to base 36.at n=43A020164
- Pseudoprimes to base 55.at n=31A020183
- Pseudoprimes to base 69.at n=28A020197
- Pseudoprimes to base 74.at n=34A020202
- Pseudoprimes to base 75.at n=36A020203
- Strong pseudoprimes to base 16.at n=29A020242
- Strong pseudoprimes to base 69.at n=12A020295
- Strong pseudoprimes to base 74.at n=14A020300
- Strong pseudoprimes to base 81.at n=16A020307
- Strong pseudoprimes to base 82.at n=16A020308
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly seven 1's.at n=31A020443
- a(n) = least m such that if r and s in {1/1, 1/2, 1/3, ..., 1/n} satisfy r < s, then r < k/m < (k+3)/m < s for some integer k.at n=42A024843
- Numbers k such that k^2 is palindromic in base 9.at n=13A029994