28688904 has 40 divisors (see below), whose sum is σ = 80357310. Its totient is φ = 9562752.

The previous prime is 28688903. The next prime is 28688921. The reversal of 28688904 is 40988682.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 28196100 + 492804 = 5310^2 + 702^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 28688904.

It is not an unprimeable number, because it can be changed into a prime (28688903) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 21489 + ... + 22784.

Almost surely, 2^28688904 is an apocalyptic number.

28688904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

28688904 is an abundant number, since it is smaller than the sum of its proper divisors (51668406).

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

28688904 is a wasteful number, since it uses less digits than its factorization.

28688904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44291 (or 44278 counting only the distinct ones).

The product of its (nonzero) digits is 221184, while the sum is 45.

The square root of 28688904 is about 5356.2023860194. The cubic root of 28688904 is about 306.1291265874.

It can be divided in two parts, 28688 and 904, that multiplied together give a palindrome (25933952).

The spelling of 28688904 in words is "twenty-eight million, six hundred eighty-eight thousand, nine hundred four".