28405521 has 36 divisors (see below), whose sum is σ = 44507632. Its totient is φ = 17449344.

The previous prime is 28405511. The next prime is 28405523. The reversal of 28405521 is 12550482.

It is a happy number.

It is not a de Polignac number, because 28405521 - 2⁶ = 28405457 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28405523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 174186 + ... + 174348.

Almost surely, 2^28405521 is an apocalyptic number.

It is an amenable number.

28405521 is a deficient number, since it is larger than the sum of its proper divisors (16102111).

28405521 is a wasteful number, since it uses less digits than its factorization.

28405521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270 (or 250 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 28405521 is about 5329.6830112118. The cubic root of 28405521 is about 305.1178295966.

The spelling of 28405521 in words is "twenty-eight million, four hundred five thousand, five hundred twenty-one".