28931688 has 64 divisors (see below), whose sum is σ = 85104000. Its totient is φ = 9075456.

The previous prime is 28931681. The next prime is 28931759. The reversal of 28931688 is 88613982.

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

It is not an unprimeable number, because it can be changed into a prime (28931681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 268 + ... + 7611.

It is an arithmetic number, because the mean of its divisors is an integer number (1329750).

Almost surely, 2^28931688 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 28931688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42552000).

28931688 is an abundant number, since it is smaller than the sum of its proper divisors (56172312).

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

28931688 is a wasteful number, since it uses less digits than its factorization.

28931688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7911 (or 7901 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 28931688 is about 5378.8184576169. The cubic root of 28931688 is about 306.9902559976.

The spelling of 28931688 in words is "twenty-eight million, nine hundred thirty-one thousand, six hundred eighty-eight".