721664087 has 4 divisors (see below), whose sum is σ = 722478576. Its totient is φ = 720849600.

The previous prime is 721664071. The next prime is 721664107. The reversal of 721664087 is 780466127.

721664087 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.

It is a cyclic number.

It is not a de Polignac number, because 721664087 - 2⁴ = 721664071 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 (721664017) 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, 405914 + ... + 407687.

It is an arithmetic number, because the mean of its divisors is an integer number (180619644).

Almost surely, 2^721664087 is an apocalyptic number.

721664087 is a deficient number, since it is larger than the sum of its proper divisors (814489).

721664087 is an equidigital number, since it uses as much as digits as its factorization.

721664087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 814488.

The product of its (nonzero) digits is 112896, while the sum is 41.

The square root of 721664087 is about 26863.8062641912. The cubic root of 721664087 is about 896.9709224086.

The spelling of 721664087 in words is "seven hundred twenty-one million, six hundred sixty-four thousand, eighty-seven".