28133521 has 8 divisors (see below), whose sum is σ = 32080104. Its totient is φ = 24441600.

The previous prime is 28133507. The next prime is 28133527. The reversal of 28133521 is 12533182.

It can be written as a sum of positive squares in 4 ways, for example, as 2772225 + 25361296 = 1665^2 + 5036^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28133521 - 2¹¹ = 28131473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28133527) 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 7 ways as a sum of consecutive naturals, for example, 63430 + ... + 63871.

It is an arithmetic number, because the mean of its divisors is an integer number (4010013).

Almost surely, 2^28133521 is an apocalyptic number.

It is an amenable number.

28133521 is a deficient number, since it is larger than the sum of its proper divisors (3946583).

28133521 is a wasteful number, since it uses less digits than its factorization.

28133521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127331.

The product of its digits is 1440, while the sum is 25.

The square root of 28133521 is about 5304.1041656438. The cubic root of 28133521 is about 304.1408086439.

The spelling of 28133521 in words is "twenty-eight million, one hundred thirty-three thousand, five hundred twenty-one".