668256728 has 24 divisors (see below), whose sum is σ = 1263168900. Its totient is φ = 331433424.

The previous prime is 668256713. The next prime is 668256731. The reversal of 668256728 is 827652866.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 126443 + ... + 131621.

Almost surely, 2^668256728 is an apocalyptic number.

It is an amenable number.

668256728 is a deficient number, since it is larger than the sum of its proper divisors (594912172).

668256728 is a wasteful number, since it uses less digits than its factorization.

668256728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5439 (or 5308 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 50.

The square root of 668256728 is about 25850.6620418124. The cubic root of 668256728 is about 874.2744365588.

The spelling of 668256728 in words is "six hundred sixty-eight million, two hundred fifty-six thousand, seven hundred twenty-eight".