1728
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 28
- Divisor Sum
- 5080
- Proper Divisor Sum (Aliquot Sum)
- 3352
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 576
- Möbius Function
- 0
- Radical
- 6
- Omega Function (Ω)
- 9
- Little Omega Function (ω)
- 2
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
- yes
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 117
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- yes
- Achilles Number
- no
- Perfect Power
- yes
- Smooth Number
- yes
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- tausendsiebenhundertachtundzwanzig· ordinal: tausendsiebenhundertachtundzwanzigste
- English
- one thousand seven hundred twenty-eight· ordinal: 1728th
- Spanish
- mil setecientos veintiocho· ordinal: 1728º
- French
- mille sept cent vingt-huit· ordinal: mille sept cent vingt-huitième
- Italian
- millesettecentoventotto· ordinal: 1728º
- Latin
- mille septingenti viginti octo· ordinal: 1728.
- Portuguese
- mil e setecentos e vinte e oito· ordinal: 1728º
Appears in sequences
- a(n) is smallest number > a(n-1) of form a(i)*a(j), i < j < n.at n=30A000423
- The cubes: a(n) = n^3.at n=12A000578
- Jordan-Polya numbers: products of factorial numbers A000142.at n=36A001013
- Powers of 12.at n=3A001021
- Numbers that are the sum of 3 nonnegative cubes in more than 1 way.at n=12A001239
- Perfect powers: m^k where m > 0 and k >= 2.at n=52A001597
- Theta series of 28-dimensional unimodular lattice with no roots and a parity vector of norm 4.at n=3A002519
- Squares and cubes.at n=50A002760
- Self numbers divisible by sum of their digits (or, self numbers which are also Harshad numbers).at n=40A003219
- a(n) = a(n-1) + a(n-4) with a(0) = 0, a(1) = a(2) = a(3) = 1.at n=26A003269
- Values of phi(k) when phi(k) = phi(k+1).at n=14A003275
- 3-smooth numbers: numbers of the form 2^i*3^j with i, j >= 0.at n=45A003586
- Number of spanning trees in K_3 X P_n.at n=2A003690
- Number of perfect matchings (or domino tilings) in K_4 X P_n.at n=4A003769
- Degrees of irreducible representations of alternating group A_12.at n=25A003867
- Degrees of irreducible representations of symmetric group S_12.at n=43A003876
- Degrees of irreducible representations of symmetric group S_12.at n=42A003876
- Theta series of D_4 lattice; Fourier coefficients of Eisenstein series E_{gamma,2}.at n=51A004011
- Area of n-th triple of squares around a triangle.at n=5A005386
- Highly powerful numbers: numbers with record value of the product of the exponents in prime factorization (A005361).at n=13A005934