721664460 has 144 divisors (see below), whose sum is σ = 2513871360. Its totient is φ = 165732480.

The previous prime is 721664431. The next prime is 721664477. The reversal of 721664460 is 64466127.

721664460 is a `hidden beast` number, since 7 + 2 + 1 + 6 + 644 + 6 + 0 = 666.

721664460 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28029 + ... + 47211.

It is an arithmetic number, because the mean of its divisors is an integer number (17457440).

Almost surely, 2^721664460 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 721664460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1256935680).

721664460 is an abundant number, since it is smaller than the sum of its proper divisors (1792206900).

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

721664460 is a wasteful number, since it uses less digits than its factorization.

721664460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19228 (or 19223 counting only the distinct ones).

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

The square root of 721664460 is about 26863.8132066168. The cubic root of 721664460 is about 896.9710769450.

The spelling of 721664460 in words is "seven hundred twenty-one million, six hundred sixty-four thousand, four hundred sixty".