2163
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 3328
- Proper Divisor Sum (Aliquot Sum)
- 1165
- 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
- 1224
- Möbius Function
- -1
- Radical
- 2163
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 138
- 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
- Denominators of cosecant numbers: -2*(2^(2*n-1)-1)*Bernoulli(2*n).at n=51A001897
- Central polygonal numbers: a(n) = n^2 - n + 1.at n=47A002061
- Numbers k such that 17*2^k + 1 is prime.at n=10A002259
- Number of restricted 3 X 3 matrices with row and column sums n.at n=29A005045
- Number of chains in power set of n-set.at n=5A007047
- Coordination sequence T3 for Zeolite Code EUO.at n=29A008098
- Coordination sequence T1 for Zeolite Code PAU.at n=34A008219
- a(n) is the concatenation of n and 3n.at n=20A019551
- (d(n)-r(n))/5, where d = A026066 and r is the periodic sequence with fundamental period (0,3,1,0,1).at n=28A026068
- Triangular array T read by rows (9-diamondization of Pascal's triangle). Step 1: t(n,k) = sum of 9 entries in diamond-shaped subarray of Pascal's triangle having vertices C(n,k), C(n+4,k+2), C(n+2,k), C(n+2,k+2). Step 2: T(n,k) = t(n,k) - t(0,0) + 1.at n=47A026907
- Triangular array T read by rows (9-diamondization of Pascal's triangle). Step 1: t(n,k) = sum of 9 entries in diamond-shaped subarray of Pascal's triangle having vertices C(n,k), C(n+4,k+2), C(n+2,k), C(n+2,k+2). Step 2: T(n,k) = t(n,k) - t(0,0) + 1.at n=52A026907
- Numbers whose square with its last digit deleted is also a square.at n=17A031149
- Shortest edge c of (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=40A031175
- 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 30.at n=20A031528
- Lucky numbers with size of gaps equal to 10 (lower terms).at n=23A031892
- Lucky numbers that are the smallest decimal concatenations of n with n + (0,1,2,3,...).at n=42A032661
- Fractional part of square root of a(n) starts with 5: first term of runs.at n=42A034111
- Numbers for which the sum of reciprocals of digits is an integer.at n=35A034708
- Number of partitions of n into parts not of form 4k+2, 12k, 12k+3 or 12k-3.at n=47A036018
- Numbers k such that 5*k + 1 is a square.at n=41A036666