28640385 has 20 divisors (see below), whose sum is σ = 51341268. Its totient is φ = 15274656.

The previous prime is 28640377. The next prime is 28640387. The reversal of 28640385 is 58304682.

28640385 is a `hidden beast` number, since 2 + 8 + 640 + 3 + 8 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12383361 + 16257024 = 3519^2 + 4032^2 .

It is not a de Polignac number, because 28640385 - 2³ = 28640377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28640387) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 34954 + ... + 35763.

Almost surely, 2^28640385 is an apocalyptic number.

It is an amenable number.

28640385 is a deficient number, since it is larger than the sum of its proper divisors (22700883).

28640385 is an equidigital number, since it uses as much as digits as its factorization.

28640385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70734 (or 70725 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

The square root of 28640385 is about 5351.6712342968. The cubic root of 28640385 is about 305.9564528573.

The spelling of 28640385 in words is "twenty-eight million, six hundred forty thousand, three hundred eighty-five".