728309 has 4 divisors (see below), whose sum is σ = 732204. Its totient is φ = 724416.

The previous prime is 728303. The next prime is 728317. The reversal of 728309 is 903827.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 422500 + 305809 = 650^2 + 553^2 .

It is a cyclic number.

It is not a de Polignac number, because 728309 - 2⁴ = 728293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 728309.

It is not an unprimeable number, because it can be changed into a prime (728303) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1652 + ... + 2045.

It is an arithmetic number, because the mean of its divisors is an integer number (183051).

2⁷²⁸³⁰⁹ is an apocalyptic number.

It is an amenable number.

728309 is a deficient number, since it is larger than the sum of its proper divisors (3895).

728309 is a wasteful number, since it uses less digits than its factorization.

728309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3894.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 728309 is about 853.4102178906. The cubic root of 728309 is about 89.9715547966.

The spelling of 728309 in words is "seven hundred twenty-eight thousand, three hundred nine".