2111
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 5
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2112
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 2110
- Möbius Function
- -1
- Radical
- 2111
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 169
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 318
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes with 7 as smallest primitive root.at n=18A001126
- Primes in ternary.at n=18A001363
- Primes written in base 4.at n=34A004678
- Primes of the form k^2 + k + 41.at n=42A005846
- Number of connected labeled T_4-topologies with n points.at n=5A006058
- Sum of Gaussian binomial coefficients [ n,k ] for q=6.at n=4A006120
- Number of strict 5th-order maximal independent sets in path graph.at n=43A007385
- Numbers that contain only 1's and 2's. Nonempty binary strings of length n in lexicographic order.at n=22A007931
- Number of permutations that are n-2 "block reversals" away from 12...n.at n=6A007973
- Odd primes such that (3p+1)/2 and 3p+4 are also prime.at n=22A014223
- Representation of n in base of Catalan numbers (a classic greedy version).at n=36A014418
- Numbers k such that the continued fraction for sqrt(k) has period 36.at n=23A020375
- Primes that contain digits 1 and 2 only.at n=3A020450
- Smallest nonempty set S containing prime divisors of 8k+7 for each k in S.at n=31A020620
- Describe the previous term! (method B - initial term is 2).at n=2A022470
- Describe previous term from the right (method B - initial term is 1).at n=3A022481
- Primes that remain prime through 2 iterations of function f(x) = 4x + 3.at n=28A023250
- Primes that remain prime through 2 iterations of function f(x) = 9x + 10.at n=38A023268
- n written in fractional base 5/2.at n=41A024632
- Prefix primes in base 8 (written in base 8).at n=28A024768