28305728 has 56 divisors (see below), whose sum is σ = 63300864. Its totient is φ = 12441600.

The previous prime is 28305713. The next prime is 28305733. The reversal of 28305728 is 82750382.

It is a happy number.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 21176 + ... + 22472.

Almost surely, 2^28305728 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 28305728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31650432).

28305728 is an abundant number, since it is smaller than the sum of its proper divisors (34995136).

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

28305728 is a wasteful number, since it uses less digits than its factorization.

28305728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1351 (or 1341 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 28305728 is about 5320.3127727606. The cubic root of 28305728 is about 304.7601016014.

It can be divided in two parts, 2830 and 5728, that added together give a palindrome (8558).

The spelling of 28305728 in words is "twenty-eight million, three hundred five thousand, seven hundred twenty-eight".