2643
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 3528
- Proper Divisor Sum (Aliquot Sum)
- 885
- 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
- 1760
- Möbius Function
- 1
- Radical
- 2643
- 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
- 102
- 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
- a(n) = Fibonacci(n+1) + prime(n).at n=16A004398
- 11*n^2 + 11*n + 3.at n=15A006222
- Number of extreme points of the set of n X n symmetric doubly-substochastic matrices.at n=6A006848
- Coordination sequence T1 for Zeolite Code AFR.at n=39A008019
- Index of 5^n within sequence of numbers of form 2^i * 5^j.at n=47A022334
- Numbers k such that Fibonacci(k) == 2 (mod k).at n=41A023174
- Positions of record values in A030777.at n=45A030782
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 51.at n=2A031549
- Coordination sequence T4 for Zeolite Code SBS.at n=41A033611
- Numbers k such that the string 5,6 occurs in the base 9 representation of k but not of k-1.at n=35A044302
- Numbers n such that string 4,3 occurs in the base 10 representation of n but not of n-1.at n=29A044375
- Numbers n such that string 5,6 occurs in the base 9 representation of n but not of n+1.at n=35A044683
- Numbers n such that string 4,3 occurs in the base 10 representation of n but not of n+1.at n=29A044756
- Discriminants of imaginary quadratic fields with class number 10 (negated).at n=39A046007
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 22.at n=26A051987
- Numbers k such that phi(k+1) = phi(k-1).at n=42A066812
- Numbers n such that n + pi(n) is a square.at n=47A073945
- a(1) = 6; a(n) is smallest number > a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=31A074342
- a(1) = 1; then the smallest number such that both the forward and reverse n-th partial concatenation is a prime for n > 1. (Reverse concatenation is taken term-wise and not digit-wise.)at n=24A083992
- Numbers n such that n, n-1 and n-2 have the same prime signature.at n=35A086337