2731
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 13
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2732
- 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
- 2730
- Möbius Function
- -1
- Radical
- 2731
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 115
- 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
- 399
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of partitions of n in which no parts are multiples of 3.at n=35A000726
- Wagstaff primes: primes of form (2^p + 1)/3.at n=4A000979
- Jacobsthal sequence (or Jacobsthal numbers): a(n) = a(n-1) + 2*a(n-2), with a(0) = 0, a(1) = 1; also a(n) = nearest integer to 2^n/3.at n=13A001045
- Table T(n,k) in which n-th row lists prime factors of 2^n + 1 (n >= 0), with repetition.at n=25A001269
- Smallest primitive factor of 2^(2n+1) + 1.at n=6A002185
- Largest prime factor of 2^n + 1.at n=13A002587
- Largest primitive factor of 2^(2n+1) + 1.at n=6A002589
- Divisors of 2^26 - 1.at n=2A003534
- a(2*n) = 2*a(2*n-1), a(2*n+1) = 2*a(2*n)-1.at n=13A005578
- Related to representations as sums of Fibonacci numbers.at n=42A006133
- a(n) = (2^(2*n + 1) + 1)/3.at n=6A007583
- Numbers n such that game of n X n Button Madness need have no solution; this lists only the primitive elements of the set.at n=9A007802
- Coordination sequence T1 for Zeolite Code EMT.at n=43A008086
- Coordination sequence T1 for Zeolite Code MTW.at n=34A008196
- Gaussian binomial coefficient [ n,12 ] for q=-2.at n=1A015423
- A015938(n)-2^n.at n=32A015939
- Cyclotomic polynomials at x=2.at n=26A019320
- Cyclotomic polynomials at x=-2.at n=13A020501
- Difference sequence of A020991.at n=63A022156
- a(n) = C(n,0) + C(n,3) + ... + C(n,3[n/3]).at n=13A024493