664897728 has 112 divisors (see below), whose sum is σ = 1942770816. Its totient is φ = 199004160.

The previous prime is 664897721. The next prime is 664897741. The reversal of 664897728 is 827798466.

It is not an unprimeable number, because it can be changed into a prime (664897721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 173400 + ... + 177192.

It is an arithmetic number, because the mean of its divisors is an integer number (17346168).

Almost surely, 2^664897728 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 664897728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (971385408).

664897728 is an abundant number, since it is smaller than the sum of its proper divisors (1277873088).

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

664897728 is a wasteful number, since it uses less digits than its factorization.

664897728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3902 (or 3892 counting only the distinct ones).

The product of its digits is 8128512, while the sum is 57.

The square root of 664897728 is about 25785.6108711816. The cubic root of 664897728 is about 872.8071252061.

The spelling of 664897728 in words is "six hundred sixty-four million, eight hundred ninety-seven thousand, seven hundred twenty-eight".