28666728 has 24 divisors (see below), whose sum is σ = 77639250. Its totient is φ = 9555552.

The previous prime is 28666727. The next prime is 28666733. The reversal of 28666728 is 82766682.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 26811684 + 1855044 = 5178^2 + 1362^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (28666721) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 199003 + ... + 199146.

Almost surely, 2^28666728 is an apocalyptic number.

It is an amenable number.

28666728 is an abundant number, since it is smaller than the sum of its proper divisors (48972522).

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

28666728 is a wasteful number, since it uses less digits than its factorization.

28666728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398161 (or 398154 counting only the distinct ones).

The product of its digits is 387072, while the sum is 45.

The square root of 28666728 is about 5354.1318624031. The cubic root of 28666728 is about 306.0502288430.

The spelling of 28666728 in words is "twenty-eight million, six hundred sixty-six thousand, seven hundred twenty-eight".