28647221 has 2 divisors, whose sum is σ = 28647222. Its totient is φ = 28647220.

The previous prime is 28647209. The next prime is 28647341. The reversal of 28647221 is 12274682.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23872996 + 4774225 = 4886^2 + 2185^2 .

It is a cyclic number.

It is not a de Polignac number, because 28647221 - 2²² = 24452917 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28647721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14323610 + 14323611.

It is an arithmetic number, because the mean of its divisors is an integer number (14323611).

Almost surely, 2^28647221 is an apocalyptic number.

It is an amenable number.

28647221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28647221 is an equidigital number, since it uses as much as digits as its factorization.

28647221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10752, while the sum is 32.

The square root of 28647221 is about 5352.3098751847. The cubic root of 28647221 is about 305.9807932183.

The spelling of 28647221 in words is "twenty-eight million, six hundred forty-seven thousand, two hundred twenty-one".