663991728 has 40 divisors (see below), whose sum is σ = 1770648576. Its totient is φ = 214190400.

The previous prime is 663991717. The next prime is 663991733. The reversal of 663991728 is 827199366.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 221628 + ... + 224603.

Almost surely, 2^663991728 is an apocalyptic number.

It is an amenable number.

663991728 is an abundant number, since it is smaller than the sum of its proper divisors (1106656848).

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

663991728 is a wasteful number, since it uses less digits than its factorization.

663991728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 446273 (or 446267 counting only the distinct ones).

The product of its digits is 979776, while the sum is 51.

The square root of 663991728 is about 25768.0369450216. The cubic root of 663991728 is about 872.4105114799.

The spelling of 663991728 in words is "six hundred sixty-three million, nine hundred ninety-one thousand, seven hundred twenty-eight".