2081
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
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2082
- 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
- 2080
- Möbius Function
- -1
- Radical
- 2081
- 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
- 63
- 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
- 313
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Numbers that are the sum of 4 positive 5th powers.at n=26A003349
- Class 4+ primes (for definition see A005105).at n=36A005108
- From relations between Siegel theta series.at n=22A006476
- Prime quadruples: numbers k such that k, k+2, k+6, k+8 are all prime.at n=7A007530
- Crystal ball sequence for planar net 4.8.8.at n=39A008577
- If x and y are terms, so is x*y + 9.at n=17A009350
- Coordination sequence T2 for Zeolite Code DFO.at n=35A009876
- Expansion of 1/(1-x^4-x^5-x^6-x^7-x^8-x^9-x^10-x^11-x^12-x^13).at n=30A017835
- Numbers k such that the continued fraction for sqrt(k) has period 11.at n=20A020350
- Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.at n=22A021005
- Initial members of prime triples (p, p+2, p+6).at n=24A022004
- Primes that remain prime through 2 iterations of function f(x) = 6x + 1.at n=24A023256
- Least m such that if r and s in {1/2, 1/5, 1/8,..., 1/(3n-1)}, satisfy r < s, then r < k/m < s for some integer k.at n=30A024823
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = A014306.at n=27A025097
- Squarefree n such that Q(sqrt(n)) has class number 5.at n=16A029705
- Previous prime concatenated with this prime p is a prime.at n=43A030460
- a(n) = prime(9*n - 2).at n=34A031383
- a(n) = prime(8*n - 7).at n=39A031915
- a(n) = prime(10*n-7).at n=31A031917
- Upper prime of a difference of 12 between consecutive primes.at n=19A031931