728321 has 8 divisors (see below), whose sum is σ = 806304. Its totient is φ = 652320.

The previous prime is 728317. The next prime is 728333. The reversal of 728321 is 123827.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 728321 - 2² = 728317 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (728381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 350 + ... + 1256.

It is an arithmetic number, because the mean of its divisors is an integer number (100788).

2⁷²⁸³²¹ is an apocalyptic number.

It is an amenable number.

728321 is a deficient number, since it is larger than the sum of its proper divisors (77983).

728321 is a wasteful number, since it uses less digits than its factorization.

728321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991.

The product of its digits is 672, while the sum is 23.

The square root of 728321 is about 853.4172484781. The cubic root of 728321 is about 89.9720489334.

The spelling of 728321 in words is "seven hundred twenty-eight thousand, three hundred twenty-one".