28587221 has 8 divisors (see below), whose sum is σ = 30870840. Its totient is φ = 26315712.

The previous prime is 28587203. The next prime is 28587253. The reversal of 28587221 is 12278582.

It can be written as a sum of positive squares in 4 ways, for example, as 1234321 + 27352900 = 1111^2 + 5230^2 .

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 28587221 - 2¹⁴ = 28570837 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28587121) 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 7 ways as a sum of consecutive naturals, for example, 2231 + ... + 7883.

It is an arithmetic number, because the mean of its divisors is an integer number (3858855).

Almost surely, 2^28587221 is an apocalyptic number.

It is an amenable number.

28587221 is a deficient number, since it is larger than the sum of its proper divisors (2283619).

28587221 is a wasteful number, since it uses less digits than its factorization.

28587221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6055.

The product of its digits is 17920, while the sum is 35.

The square root of 28587221 is about 5346.7018805989. The cubic root of 28587221 is about 305.7670240279.

The spelling of 28587221 in words is "twenty-eight million, five hundred eighty-seven thousand, two hundred twenty-one".