66666728 has 16 divisors (see below), whose sum is σ = 126761760. Its totient is φ = 32863600.

The previous prime is 66666713. The next prime is 66666731. The reversal of 66666728 is 82766666.

66666728 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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58118 + ... + 59253.

It is an arithmetic number, because the mean of its divisors is an integer number (7922610).

Almost surely, 2^66666728 is an apocalyptic number.

It is an amenable number.

66666728 is a deficient number, since it is larger than the sum of its proper divisors (60095032).

66666728 is a wasteful number, since it uses less digits than its factorization.

66666728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117448 (or 117444 counting only the distinct ones).

The product of its digits is 870912, while the sum is 47.

The square root of 66666728 is about 8164.9695651607. The cubic root of 66666728 is about 405.4802573854.

The spelling of 66666728 in words is "sixty-six million, six hundred sixty-six thousand, seven hundred twenty-eight".