723128821 has 2 divisors, whose sum is σ = 723128822. Its totient is φ = 723128820.

The previous prime is 723128797. The next prime is 723128863. The reversal of 723128821 is 128821327.

723128821 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., 699020721 + 24108100 = 26439^2 + 4910^2 .

It is an emirp because it is prime and its reverse (128821327) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 723128821 - 2²⁹ = 186257909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (723128321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 361564410 + 361564411.

It is an arithmetic number, because the mean of its divisors is an integer number (361564411).

Almost surely, 2^723128821 is an apocalyptic number.

It is an amenable number.

723128821 is a deficient number, since it is larger than the sum of its proper divisors (1).

723128821 is an equidigital number, since it uses as much as digits as its factorization.

723128821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10752, while the sum is 34.

The square root of 723128821 is about 26891.0546650740. The cubic root of 723128821 is about 897.5773614980.

The spelling of 723128821 in words is "seven hundred twenty-three million, one hundred twenty-eight thousand, eight hundred twenty-one".