28345728 has 64 divisors (see below), whose sum is σ = 76169520. Its totient is φ = 9338880.

The previous prime is 28345727. The next prime is 28345741. The reversal of 28345728 is 82754382.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28345721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36868 + ... + 37628.

Almost surely, 2^28345728 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 28345728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38084760).

28345728 is an abundant number, since it is smaller than the sum of its proper divisors (47823792).

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

28345728 is an equidigital number, since it uses as much as digits as its factorization.

28345728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 875 (or 863 counting only the distinct ones).

The product of its digits is 107520, while the sum is 39.

The square root of 28345728 is about 5324.0706231229. The cubic root of 28345728 is about 304.9035904189.

The spelling of 28345728 in words is "twenty-eight million, three hundred forty-five thousand, seven hundred twenty-eight".