28575621 has 12 divisors (see below), whose sum is σ = 41516748. Its totient is φ = 18939264.

The previous prime is 28575619. The next prime is 28575629. The reversal of 28575621 is 12657582.

It is a happy number.

28575621 is a `hidden beast` number, since 28 + 5 + 7 + 5 + 621 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12173121 + 16402500 = 3489^2 + 4050^2 .

It is not a de Polignac number, because 28575621 - 2¹ = 28575619 is a prime.

It is a super-2 number, since 2×28575621² = 1633132231071282, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28575629) by changing a digit.

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, 7620 + ... + 10733.

It is an arithmetic number, because the mean of its divisors is an integer number (3459729).

Almost surely, 2^28575621 is an apocalyptic number.

It is an amenable number.

28575621 is a deficient number, since it is larger than the sum of its proper divisors (12941127).

28575621 is a wasteful number, since it uses less digits than its factorization.

28575621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18532 (or 18529 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 28575621 is about 5345.6169896468. The cubic root of 28575621 is about 305.7256608219.

The spelling of 28575621 in words is "twenty-eight million, five hundred seventy-five thousand, six hundred twenty-one".