28017221 has 2 divisors, whose sum is σ = 28017222. Its totient is φ = 28017220.

The previous prime is 28017203. The next prime is 28017233. The reversal of 28017221 is 12271082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23961025 + 4056196 = 4895^2 + 2014^2 .

It is a cyclic number.

It is not a de Polignac number, because 28017221 - 2¹⁴ = 28000837 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 (28017721) 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 as a sum of consecutive naturals, namely, 14008610 + 14008611.

It is an arithmetic number, because the mean of its divisors is an integer number (14008611).

Almost surely, 2^28017221 is an apocalyptic number.

It is an amenable number.

28017221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28017221 is an equidigital number, since it uses as much as digits as its factorization.

28017221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 28017221 is about 5293.1296035521. The cubic root of 28017221 is about 303.7211381181.

The spelling of 28017221 in words is "twenty-eight million, seventeen thousand, two hundred twenty-one".