728764921 has 4 divisors (see below), whose sum is σ = 734328144. Its totient is φ = 723201700.

The previous prime is 728764919. The next prime is 728764937. The reversal of 728764921 is 129467827.

728764921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 728764921 - 2¹ = 728764919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (728762921) 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, 2781415 + ... + 2781676.

It is an arithmetic number, because the mean of its divisors is an integer number (183582036).

Almost surely, 2^728764921 is an apocalyptic number.

It is an amenable number.

728764921 is a deficient number, since it is larger than the sum of its proper divisors (5563223).

728764921 is a wasteful number, since it uses less digits than its factorization.

728764921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5563222.

The product of its digits is 338688, while the sum is 46.

The square root of 728764921 is about 26995.6463341777. The cubic root of 728764921 is about 899.9032492704.

The spelling of 728764921 in words is "seven hundred twenty-eight million, seven hundred sixty-four thousand, nine hundred twenty-one".