28970021 has 2 divisors, whose sum is σ = 28970022. Its totient is φ = 28970020.

The previous prime is 28970017. The next prime is 28970077. The reversal of 28970021 is 12007982.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22137025 + 6832996 = 4705^2 + 2614^2 .

It is a cyclic number.

It is not a de Polignac number, because 28970021 - 2² = 28970017 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 (28970321) 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, 14485010 + 14485011.

It is an arithmetic number, because the mean of its divisors is an integer number (14485011).

Almost surely, 2^28970021 is an apocalyptic number.

It is an amenable number.

28970021 is a deficient number, since it is larger than the sum of its proper divisors (1).

28970021 is an equidigital number, since it uses as much as digits as its factorization.

28970021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 28970021 is about 5382.3806071292. The cubic root of 28970021 is about 307.1257782669.

The spelling of 28970021 in words is "twenty-eight million, nine hundred seventy thousand, twenty-one".