28121521 has 2 divisors, whose sum is σ = 28121522. Its totient is φ = 28121520.

The previous prime is 28121497. The next prime is 28121581. The reversal of 28121521 is 12512182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24750625 + 3370896 = 4975^2 + 1836^2 .

It is a cyclic number.

It is not a de Polignac number, because 28121521 - 2¹³ = 28113329 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 28121492 and 28121501.

It is not a weakly prime, because it can be changed into another prime (28121581) 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, 14060760 + 14060761.

It is an arithmetic number, because the mean of its divisors is an integer number (14060761).

Almost surely, 2^28121521 is an apocalyptic number.

It is an amenable number.

28121521 is a deficient number, since it is larger than the sum of its proper divisors (1).

28121521 is an equidigital number, since it uses as much as digits as its factorization.

28121521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 22.

The square root of 28121521 is about 5302.9728454896. The cubic root of 28121521 is about 304.0975600138.

The spelling of 28121521 in words is "twenty-eight million, one hundred twenty-one thousand, five hundred twenty-one".