2861
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2862
- 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
- 2860
- Möbius Function
- -1
- Radical
- 2861
- 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
- 27
- 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
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 416
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes of the form k^2 - k - 1.at n=29A002327
- From relations between Siegel theta series.at n=35A006476
- Numbers n such that n! has a square number of digits.at n=41A006488
- Coordination sequence T3 for Zeolite Code LTN.at n=37A008142
- Coordination sequence T2 for Cordierite.at n=32A008252
- Coordination sequence T4 for Zeolite Code RTH.at n=37A009896
- Four-fold exponential convolution of primes with themselves (divided by 8).at n=4A014351
- Numbers k such that the continued fraction for sqrt(k) has period 49.at n=4A020388
- n-th prime p(k) such that p(k) + p(k+9) = p(k+3) + p(k+6).at n=35A022893
- a(n) = A027113(n, n+4).at n=6A027117
- a(n) = A027113(n, 2n-6).at n=7A027124
- Golc sequence in base 2. Left to right concatenation of n,int(log_2(n)),int(log_2(int(log_2(n)))),... in base 2.at n=43A028432
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 5.at n=18A031418
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 22 ones.at n=32A031790
- a(n) = prime(10*n - 4).at n=41A031905
- Lower prime of a difference of 18 between consecutive primes.at n=8A031936
- Numbers k such that 209*2^k+1 is prime.at n=10A032481
- Positive numbers having the same set of digits in base 6 and base 7.at n=36A033170
- Primes of form x^2+65*y^2.at n=18A033241
- Scan decimal expansion of zeta(3) until all n-digit strings have been seen; a(n) is last string seen.at n=3A036902