2169
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 3146
- Proper Divisor Sum (Aliquot Sum)
- 977
- 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
- 1440
- Möbius Function
- 0
- Radical
- 723
- Omega Function (Ω)
- 3
- 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
- 76
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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) = 2^n + n^2.at n=11A001580
- Divisors of 2^24 - 1.at n=43A003532
- Number of 2-factors in C_4 X P_n.at n=4A003698
- a(n)=least number m such that m-a(n-1)<>a(j)-a(k) for all j,k less than m; a(1)=1, a(2)=3.at n=44A004979
- Coordination sequence T4 for Zeolite Code SGT.at n=29A008232
- Coordination sequence T3 for Zeolite Code -CLO.at n=41A009852
- Coefficients in expansion of e as Sum_{n>=1} a(n)/(n*n!*(n+1)!), as found by greedy algorithm.at n=46A011189
- Pseudoprimes to base 8.at n=33A020137
- Numbers k such that the continued fraction for sqrt(k) has period 38.at n=15A020377
- Number of 2's in n-th term of A022470.at n=30A022473
- Numbers k such that Fibonacci(k) == 34 (mod k).at n=22A023180
- a(n) = position of 3*n^2 in sequence A025051 (numbers of form j*k + k*i + i*j, without repetitions, where 1 <= i <= j <= k).at n=26A025056
- a(n) = n^2 + n + 7.at n=46A027692
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 20 ones.at n=29A031788
- Numbers whose base-15 expansion has no run of digits with length < 2.at n=22A033028
- Coordination sequence T1 for Zeolite Code SBS.at n=37A033608
- a(1) = 1; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=30A033680
- a(n+1) = a(n) + sum of squares of digits of a(n).at n=34A033936
- Number of partitions of n such that cn(0,5) = cn(1,5) <= cn(3,5) <= cn(2,5) = cn(4,5).at n=61A036864
- Numbers n such that n and n+1 are differences between 2 positive cubes in at least one way.at n=3A038594