2135
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 2976
- Proper Divisor Sum (Aliquot Sum)
- 841
- 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
- -1
- Radical
- 2135
- 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
- 63
- 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
- If F(n) is the n-th Fibonacci number, then a(2n) = (F(2n+1) + F(n+2))/2 and a(2n+1) = (F(2n+2) + F(n+1))/2.at n=17A001224
- Expansion of (1+x^3)/((1-x)*(1-x^2)^2*(1-x^3)).at n=40A001973
- Expansion of 1/((1-x)^4*(1+x)).at n=27A002623
- Number of basic invariants for cyclic group of order and degree n.at n=15A002956
- a(n) = (F(2*n-1) + F(n+1))/2 where F(n) is a Fibonacci number.at n=10A005207
- Coordination sequence T1 for Zeolite Code AFR.at n=35A008019
- Coordination sequence T1 for Zeolite Code LTL.at n=34A008138
- Coordination sequence T3 for Zeolite Code LTN.at n=32A008142
- Expansion of (1+x^5)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=51A008766
- a(n) = n*(n+1)*(4*n+5)/6.at n=14A016061
- From George Gilbert's marks problem: jumping 7 marks at a time (initial positions).at n=18A019997
- Number of 3's in n-th term of A022470.at n=32A022474
- a(n) = 1*(n+1-1) + 2*(n+1-2) + ... + k*(n+1-k), where k = floor((n+1)/2).at n=27A023856
- a(n) = 1*(n+3-1) + 2*(n+3-2) + .... + k*(n+3-k), where k=floor((n+1)/2).at n=26A023857
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = A023532, t = (1, p(1), p(2), ...).at n=42A024369
- Prefix primes in base 8 (written in base 8).at n=30A024768
- Every suffix prime and no 0 digits in base 6 (written in base 6).at n=27A024781
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers), t = (natural numbers >= 2).at n=26A024853
- Numbers k such that the continued fraction for sqrt(k) has even period 2*m and the m-th term of the periodic part is 5.at n=44A031408
- "BHK" (reversible, identity, unlabeled) transform of 2,2,2,2,...at n=7A032096