2729
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 2730
- 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
- 2728
- Möbius Function
- -1
- Radical
- 2729
- 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
- 159
- 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
- 398
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Smallest nonnegative number that is the sum of 3 squares in exactly n ways.at n=20A000437
- Number of primes < prime(n)^2.at n=36A000879
- Numbers that are the sum of 3 nonnegative cubes in more than 1 way.at n=27A001239
- a(n) = n^2 + prime(n).at n=49A004232
- a(n) = ceiling(n*phi^15), where phi is the golden ratio, A001622.at n=2A004970
- Prime self (or Colombian) numbers: primes not expressible as the sum of an integer and its digit sum.at n=42A006378
- Coordination sequence T1 for Zeolite Code DOH.at n=32A008078
- Numbers that are the sum of 3 positive cubes in more than one way.at n=19A008917
- sech(arctan(arctanh(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+2729/8!*x^8...at n=4A012239
- Numbers k such that the continued fraction for sqrt(k) has period 45.at n=5A020384
- n-th prime p(k) such that p(k) + p(k+9) = p(k+3) + p(k+6).at n=33A022893
- Primes that remain prime through 2 iterations of function f(x) = 8x + 9.at n=24A023264
- a(n) = least m such that if r and s in {F(h)/F(2*h): h = 1,2,...,n} satisfy r < s, then r < k/m < s for some integer k, where F = A000045 (Fibonacci numbers).at n=15A024831
- a(n) = least m such that if r and s in {|F(h+1)-tau*F(h)|: h = 1,2,...,n} satisfy r < s, then r < k/m < s for some integer k, where F = A000045 (Fibonacci numbers) and tau = (1+sqrt(5))/2 (golden ratio).at n=15A024849
- a(n) = [ 2nd elementary symmetric function of {sqrt(k)} ], k = 1,2,...,n.at n=21A025193
- Numbers that are the sum of 3 positive cubes in exactly 2 ways.at n=19A025396
- a(n) = Sum_{k=0..n} T(n,k) * T(n,2n-k), with T given by A027113.at n=6A027135
- Smallest prime containing n-th square as substring.at n=27A029948
- Smallest prime containing n-th cube as substring.at n=9A029949
- Primes that are palindromic in base 14.at n=30A029981