728449621 has 2 divisors, whose sum is σ = 728449622. Its totient is φ = 728449620.

The previous prime is 728449619. The next prime is 728449633. The reversal of 728449621 is 126944827.

728449621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 453221521 + 275228100 = 21289^2 + 16590^2 .

It is an emirp because it is prime and its reverse (126944827) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 728449621 - 2¹ = 728449619 is a prime.

Together with 728449619, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (728449651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364224810 + 364224811.

It is an arithmetic number, because the mean of its divisors is an integer number (364224811).

Almost surely, 2^728449621 is an apocalyptic number.

It is an amenable number.

728449621 is a deficient number, since it is larger than the sum of its proper divisors (1).

728449621 is an equidigital number, since it uses as much as digits as its factorization.

728449621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 43.

The square root of 728449621 is about 26989.8058718472. The cubic root of 728449621 is about 899.7734495613.

The spelling of 728449621 in words is "seven hundred twenty-eight million, four hundred forty-nine thousand, six hundred twenty-one".