2741
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2742
- 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
- 2740
- Möbius Function
- -1
- Radical
- 2741
- 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
- 128
- 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 400
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- G.f.: Product_{k>=1} (1 + x^(2*k - 1)) / (1 - x^(2*k)).at n=36A006950
- a(n) = prime(n^2).at n=19A011757
- a(n) = floor( n*(n-1)*(n-2)/20 ).at n=39A011902
- Number of ordered quadruples of integers from [ 1,n ] with no common factors between pairs.at n=27A015636
- Expansion of g.f. 1/((1-2*x)*(1-3*x)*(1-12*x)).at n=3A016281
- Expansion of 1/(1-x^10-x^11-x^12-x^13-x^14-x^15-x^16-x^17-x^18-x^19).at n=63A017895
- Powers of fifth root of 21 rounded up.at n=13A018176
- Numbers k such that the continued fraction for sqrt(k) has period 43.at n=5A020382
- The sequence m(n) in A022905.at n=32A022907
- Primes that remain prime through 2 iterations of function f(x) = 8x + 1.at n=12A023260
- Primes that remain prime through 2 iterations of function f(x) = 9x + 2.at n=40A023265
- Primes that remain prime through 3 iterations of function f(x) = 9x + 2.at n=13A023296
- a(n) = least m such that if r and s in {F(2*h)/F(2*h+1): h = 1,2,...,n} satisfy r < s, then r < k/m < s for some integer k, where F = A000045 (Fibonacci numbers).at n=4A024830
- a(n) = Sum_{k=0..floor(n/2)} T(n-k,k), T given by A026747.at n=15A026757
- Coordination sequence T2 for Zeolite Code ITE.at n=36A027370
- Positions of record values in A030787.at n=48A030792
- a(n) = prime(10*n).at n=39A031343
- 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 3.at n=37A031416
- a(n) = prime(100*n).at n=3A031921
- Lower prime of a difference of 8 between consecutive primes.at n=36A031926