28012121 has 2 divisors, whose sum is σ = 28012122. Its totient is φ = 28012120.

The previous prime is 28012111. The next prime is 28012133. The reversal of 28012121 is 12121082.

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., 18800896 + 9211225 = 4336^2 + 3035^2 .

It is a cyclic number.

It is not a de Polignac number, because 28012121 - 2¹⁰ = 28011097 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28012121.

It is not a weakly prime, because it can be changed into another prime (28012111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14006060 + 14006061.

It is an arithmetic number, because the mean of its divisors is an integer number (14006061).

Almost surely, 2^28012121 is an apocalyptic number.

It is an amenable number.

28012121 is a deficient number, since it is larger than the sum of its proper divisors (1).

28012121 is an equidigital number, since it uses as much as digits as its factorization.

28012121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 28012121 is about 5292.6478250494. The cubic root of 28012121 is about 303.7027081222.

The spelling of 28012121 in words is "twenty-eight million, twelve thousand, one hundred twenty-one".