28289640 has 32 divisors (see below), whose sum is σ = 84869280. Its totient is φ = 7543872.

The previous prime is 28289627. The next prime is 28289647. The reversal of 28289640 is 4698282.

It is not an unprimeable number, because it can be changed into a prime (28289647) 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, 117754 + ... + 117993.

It is an arithmetic number, because the mean of its divisors is an integer number (2652165).

Almost surely, 2^28289640 is an apocalyptic number.

28289640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28289640 is an abundant number, since it is smaller than the sum of its proper divisors (56579640).

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

28289640 is a wasteful number, since it uses less digits than its factorization.

28289640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235761 (or 235757 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 39.

The square root of 28289640 is about 5318.8006166804. The cubic root of 28289640 is about 304.7023522806.

The spelling of 28289640 in words is "twenty-eight million, two hundred eighty-nine thousand, six hundred forty".