721332864 has 192 divisors, whose sum is σ = 2460843840. Its totient is φ = 206032896.

The previous prime is 721332847. The next prime is 721332881. The reversal of 721332864 is 468233127.

It is a happy number.

721332864 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (721332847) and next prime (721332881).

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×721332864² = 1040642201372884992, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a zygodrome in base 4.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 216072 + ... + 219384.

It is an arithmetic number, because the mean of its divisors is an integer number (12816895).

Almost surely, 2^721332864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721332864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1230421920).

721332864 is an abundant number, since it is smaller than the sum of its proper divisors (1739510976).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721332864 is an equidigital number, since it uses as much as digits as its factorization.

721332864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3349 (or 3325 counting only the distinct ones).

The product of its digits is 48384, while the sum is 36.

The square root of 721332864 is about 26857.6407005530. The cubic root of 721332864 is about 896.8336734817.

The spelling of 721332864 in words is "seven hundred twenty-one million, three hundred thirty-two thousand, eight hundred sixty-four".