723512821 has 4 divisors (see below), whose sum is σ = 724006144. Its totient is φ = 723019500.

The previous prime is 723512807. The next prime is 723512831. The reversal of 723512821 is 128215327.

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 723512821 - 2⁵ = 723512789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (723512831) 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, 244455 + ... + 247396.

It is an arithmetic number, because the mean of its divisors is an integer number (181001536).

Almost surely, 2^723512821 is an apocalyptic number.

It is an amenable number.

723512821 is a deficient number, since it is larger than the sum of its proper divisors (493323).

723512821 is a wasteful number, since it uses less digits than its factorization.

723512821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493322.

The product of its digits is 6720, while the sum is 31.

The square root of 723512821 is about 26898.1936382353. The cubic root of 723512821 is about 897.7362122704.

The spelling of 723512821 in words is "seven hundred twenty-three million, five hundred twelve thousand, eight hundred twenty-one".