729009 has 6 divisors (see below), whose sum is σ = 1053026. Its totient is φ = 486000.

The previous prime is 728993. The next prime is 729019. The reversal of 729009 is 900927.

It can be written as a sum of positive squares in only one way, i.e., 705600 + 23409 = 840^2 + 153^2 .

It is not a de Polignac number, because 729009 - 2⁴ = 728993 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (729019) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 40492 + ... + 40509.

729009 is a Friedman number, since it can be written as 90^(7^0+2)+9, using all its digits and the basic arithmetic operations.

2⁷²⁹⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

729009 is a deficient number, since it is larger than the sum of its proper divisors (324017).

729009 is a wasteful number, since it uses less digits than its factorization.

729009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81007 (or 81004 counting only the distinct ones).

The product of its (nonzero) digits is 1134, while the sum is 27.

The square root of 729009 is about 853.8202386920. The cubic root of 729009 is about 90.0003703688. Note that the first 3 decimals are identical.

It can be divided in two parts, 72900 and 9, that multiplied together give a square (656100 = 810²).

The spelling of 729009 in words is "seven hundred twenty-nine thousand, nine".