• 729 can be written using four 4's:

729 has 7 divisors (see below), whose sum is σ = 1093. Its totient is φ = 486.

The previous prime is 727. The next prime is 733. The reversal of 729 is 927.

729 = T_{26} + T_{27}.

The square root of 729 is 27.

The cubic root of 729 is 9.

It is a perfect power (a square, a cube, a 6-th power), and thus also a powerful number.

729 is nontrivially palindromic in base 8.

It is not a de Polignac number, because 729 - 2^{1} = 727 is a prime.

It is a Smith number, since the sum of its digits (18) coincides with the sum of the digits of its prime factors.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

Its product of digits (126) is a multiple of the sum of its prime divisors (3).

It is a Curzon number.

729 is a lucky number.

It is a plaindrome in base 15.

It is a nialpdrome in base 3, base 9 and base 13.

It is not an unprimeable number, because it can be changed into a prime (727) by changing a digit.

It is a polite number, since it can be written in 6 ways as a sum of consecutive naturals, for example, 242 + 243 + 244.

729 is the 27-th square number.

729 is the 14-th centered octagonal number.

It is an amenable number.

729 is a deficient number, since it is larger than the sum of its proper divisors (364).

729 is an frugal number, since it uses more digits than its factorization.

729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18 (or 3 counting only the distinct ones).

The product of its digits is 126, while the sum is 18.

Adding to 729 its sum of digits (18), we get a palindrome (747).

It can be divided in two parts, 72 and 9, that added together give a 4-th power (81 = 3^{4}).

The spelling of 729 in words is "seven hundred twenty-nine", and thus it is an aban number and an oban number.

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