28133440 has 28 divisors (see below), whose sum is σ = 66993516. Its totient is φ = 11253248.

The previous prime is 28133437. The next prime is 28133459. The reversal of 28133440 is 4433182.

It can be written as a sum of positive squares in 2 ways, for example, as 10291264 + 17842176 = 3208^2 + 4224^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43639 + ... + 44278.

Almost surely, 2^28133440 is an apocalyptic number.

28133440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28133440 is an abundant number, since it is smaller than the sum of its proper divisors (38860076).

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

28133440 is an equidigital number, since it uses as much as digits as its factorization.

28133440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87934 (or 87924 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 28133440 is about 5304.0965300417. The cubic root of 28133440 is about 304.1405167569.

The spelling of 28133440 in words is "twenty-eight million, one hundred thirty-three thousand, four hundred forty".