28705640 has 32 divisors (see below), whose sum is σ = 64800000. Its totient is φ = 11444544.

The previous prime is 28705631. The next prime is 28705657. The reversal of 28705640 is 4650782.

It is a junction number, because it is equal to n+sod(n) for n = 28705597 and 28705606.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13361 + ... + 15359.

It is an arithmetic number, because the mean of its divisors is an integer number (2025000).

Almost surely, 2^28705640 is an apocalyptic number.

28705640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28705640 is an abundant number, since it is smaller than the sum of its proper divisors (36094360).

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

28705640 is a wasteful number, since it uses less digits than its factorization.

28705640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2369 (or 2365 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 32.

The square root of 28705640 is about 5357.7644591751. The cubic root of 28705640 is about 306.1886429905.

The spelling of 28705640 in words is "twenty-eight million, seven hundred five thousand, six hundred forty".