28021888 has 32 divisors (see below), whose sum is σ = 57757500. Its totient is φ = 13526016.

The previous prime is 28021883. The next prime is 28021897. The reversal of 28021888 is 88812082.

It can be written as a sum of positive squares in 2 ways, for example, as 26956864 + 1065024 = 5192^2 + 1032^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (28021883) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63 + ... + 7486.

Almost surely, 2^28021888 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 28021888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28878750).

28021888 is an abundant number, since it is smaller than the sum of its proper divisors (29735612).

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

28021888 is an equidigital number, since it uses as much as digits as its factorization.

28021888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7592 (or 7580 counting only the distinct ones).

The product of its (nonzero) digits is 16384, while the sum is 37.

The square root of 28021888 is about 5293.5704396938. The cubic root of 28021888 is about 303.7380014115.

The spelling of 28021888 in words is "twenty-eight million, twenty-one thousand, eight hundred eighty-eight".