721908864 has 96 divisors (see below), whose sum is σ = 2088569340. Its totient is φ = 239339520.

The previous prime is 721908841. The next prime is 721908883. The reversal of 721908864 is 468809127.

It can be written as a sum of positive squares in 2 ways, for example, as 718668864 + 3240000 = 26808^2 + 1800^2 .

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225354 + ... + 228534.

Almost surely, 2^721908864 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 721908864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1044284670).

721908864 is an abundant number, since it is smaller than the sum of its proper divisors (1366660476).

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

721908864 is a wasteful number, since it uses less digits than its factorization.

721908864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3398 (or 3383 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 721908864 is about 26868.3617662112. The cubic root of 721908864 is about 897.0723237099.

The spelling of 721908864 in words is "seven hundred twenty-one million, nine hundred eight thousand, eight hundred sixty-four".