728509 has 4 divisors (see below), whose sum is σ = 753660. Its totient is φ = 703360.

The previous prime is 728489. The next prime is 728521. The reversal of 728509 is 905827.

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 356409 + 372100 = 597^2 + 610^2 .

It is a cyclic number.

It is not a de Polignac number, because 728509 - 2⁵ = 728477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728579) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12532 + ... + 12589.

It is an arithmetic number, because the mean of its divisors is an integer number (188415).

2⁷²⁸⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

728509 is a deficient number, since it is larger than the sum of its proper divisors (25151).

728509 is a wasteful number, since it uses less digits than its factorization.

728509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25150.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 728509 is about 853.5273867897. The cubic root of 728509 is about 89.9797897006.

The spelling of 728509 in words is "seven hundred twenty-eight thousand, five hundred nine".