28345021 has 2 divisors, whose sum is σ = 28345022. Its totient is φ = 28345020.

The previous prime is 28345013. The next prime is 28345061. The reversal of 28345021 is 12054382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27941796 + 403225 = 5286^2 + 635^2 .

It is a cyclic number.

It is not a de Polignac number, because 28345021 - 2³ = 28345013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28345061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14172510 + 14172511.

It is an arithmetic number, because the mean of its divisors is an integer number (14172511).

Almost surely, 2^28345021 is an apocalyptic number.

It is an amenable number.

28345021 is a deficient number, since it is larger than the sum of its proper divisors (1).

28345021 is an equidigital number, since it uses as much as digits as its factorization.

28345021 is an evil number, because the sum of its binary digits is even.

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

The square root of 28345021 is about 5324.0042261441. The cubic root of 28345021 is about 304.9010554263.

The spelling of 28345021 in words is "twenty-eight million, three hundred forty-five thousand, twenty-one".