28191888 has 70 divisors (see below), whose sum is σ = 81929094. Its totient is φ = 9393408.

The previous prime is 28191853. The next prime is 28191893. The reversal of 28191888 is 88819182.

It can be written as a sum of positive squares in only one way, i.e., 28005264 + 186624 = 5292^2 + 432^2 .

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 10456 + ... + 12872.

Almost surely, 2^28191888 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 28191888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40964547).

28191888 is an abundant number, since it is smaller than the sum of its proper divisors (53737206).

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

28191888 is an equidigital number, since it uses as much as digits as its factorization.

28191888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2443 (or 2422 counting only the distinct ones).

The product of its digits is 73728, while the sum is 45.

The square root of 28191888 is about 5309.6033750178. The cubic root of 28191888 is about 304.3509911815.

The spelling of 28191888 in words is "twenty-eight million, one hundred ninety-one thousand, eight hundred eighty-eight".