28532221 has 4 divisors (see below), whose sum is σ = 28544992. Its totient is φ = 28519452.

The previous prime is 28532191. The next prime is 28532227. The reversal of 28532221 is 12223582.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 28532221 - 2¹⁵ = 28499453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28532227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2055 + ... + 7828.

It is an arithmetic number, because the mean of its divisors is an integer number (7136248).

Almost surely, 2^28532221 is an apocalyptic number.

It is an amenable number.

28532221 is a deficient number, since it is larger than the sum of its proper divisors (12771).

28532221 is an equidigital number, since it uses as much as digits as its factorization.

28532221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12770.

The product of its digits is 1920, while the sum is 25.

The square root of 28532221 is about 5341.5560466965. The cubic root of 28532221 is about 305.5708060169.

The spelling of 28532221 in words is "twenty-eight million, five hundred thirty-two thousand, two hundred twenty-one".