28565640 has 48 divisors (see below), whose sum is σ = 92839500. Its totient is φ = 7617408.

The previous prime is 28565633. The next prime is 28565659. The reversal of 28565640 is 4656582.

28565640 is a `hidden beast` number, since 2 + 8 + 5 + 6 + 5 + 640 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 24621444 + 3944196 = 4962^2 + 1986^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 28565595 and 28565604.

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 11 ways as a sum of consecutive naturals, for example, 39315 + ... + 40034.

Almost surely, 2^28565640 is an apocalyptic number.

28565640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28565640 is an abundant number, since it is smaller than the sum of its proper divisors (64273860).

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

28565640 is a wasteful number, since it uses less digits than its factorization.

28565640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79366 (or 79359 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The square root of 28565640 is about 5344.6833395441. The cubic root of 28565640 is about 305.6900616753.

The spelling of 28565640 in words is "twenty-eight million, five hundred sixty-five thousand, six hundred forty".