28056221 has 2 divisors, whose sum is σ = 28056222. Its totient is φ = 28056220.

The previous prime is 28056191. The next prime is 28056257. The reversal of 28056221 is 12265082.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22944100 + 5112121 = 4790^2 + 2261^2 .

It is a cyclic number.

It is not a de Polignac number, because 28056221 - 2²² = 23861917 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 (28056421) 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 as a sum of consecutive naturals, namely, 14028110 + 14028111.

It is an arithmetic number, because the mean of its divisors is an integer number (14028111).

Almost surely, 2^28056221 is an apocalyptic number.

It is an amenable number.

28056221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28056221 is an equidigital number, since it uses as much as digits as its factorization.

28056221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 28056221 is about 5296.8123432872. The cubic root of 28056221 is about 303.8619994892.

The spelling of 28056221 in words is "twenty-eight million, fifty-six thousand, two hundred twenty-one".