668563728 has 160 divisors (see below), whose sum is σ = 2028441600. Its totient is φ = 185822208.

The previous prime is 668563703. The next prime is 668563733. The reversal of 668563728 is 827365866.

668563728 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2362275 + ... + 2362557.

It is an arithmetic number, because the mean of its divisors is an integer number (12677760).

Almost surely, 2^668563728 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 668563728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1014220800).

668563728 is an abundant number, since it is smaller than the sum of its proper divisors (1359877872).

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

668563728 is a wasteful number, since it uses less digits than its factorization.

668563728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469 (or 463 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 51.

The square root of 668563728 is about 25856.5993123612. The cubic root of 668563728 is about 874.4082978676.

The spelling of 668563728 in words is "six hundred sixty-eight million, five hundred sixty-three thousand, seven hundred twenty-eight".