28105640 has 32 divisors (see below), whose sum is σ = 65421000. Its totient is φ = 10854144.

The previous prime is 28105633. The next prime is 28105643. The reversal of 28105640 is 4650182.

It can be written as a sum of positive squares in 4 ways, for example, as 17123044 + 10982596 = 4138^2 + 3314^2 .

It is not an unprimeable number, because it can be changed into a prime (28105643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10955 + ... + 13274.

Almost surely, 2^28105640 is an apocalyptic number.

28105640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28105640 is an abundant number, since it is smaller than the sum of its proper divisors (37315360).

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

28105640 is a wasteful number, since it uses less digits than its factorization.

28105640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24269 (or 24265 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 28105640 is about 5301.4752663763. The cubic root of 28105640 is about 304.0403051361.

The spelling of 28105640 in words is "twenty-eight million, one hundred five thousand, six hundred forty".