728821 has 8 divisors (see below), whose sum is σ = 777600. Its totient is φ = 681120.

The previous prime is 728813. The next prime is 728831. The reversal of 728821 is 128827.

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 728821 - 2³ = 728813 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 728821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728831) 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 7 ways as a sum of consecutive naturals, for example, 1476 + ... + 1906.

It is an arithmetic number, because the mean of its divisors is an integer number (97200).

2⁷²⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

728821 is a deficient number, since it is larger than the sum of its proper divisors (48779).

728821 is a wasteful number, since it uses less digits than its factorization.

728821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 539.

The product of its digits is 1792, while the sum is 28.

The square root of 728821 is about 853.7101381617. The cubic root of 728821 is about 89.9926331419.

The spelling of 728821 in words is "seven hundred twenty-eight thousand, eight hundred twenty-one".