28806640 has 40 divisors (see below), whose sum is σ = 68084928. Its totient is φ = 11331840.

The previous prime is 28806623. The next prime is 28806667. The reversal of 28806640 is 4660882.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 28806596 and 28806605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1929 + ... + 7831.

Almost surely, 2^28806640 is an apocalyptic number.

28806640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28806640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34042464).

28806640 is an abundant number, since it is smaller than the sum of its proper divisors (39278288).

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

28806640 is a wasteful number, since it uses less digits than its factorization.

28806640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5977 (or 5971 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 34.

The square root of 28806640 is about 5367.1817558193. The cubic root of 28806640 is about 306.5473280668.

The spelling of 28806640 in words is "twenty-eight million, eight hundred six thousand, six hundred forty".