28040209 has 2 divisors, whose sum is σ = 28040210. Its totient is φ = 28040208.

The previous prime is 28040189. The next prime is 28040227. The reversal of 28040209 is 90204082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23309584 + 4730625 = 4828^2 + 2175^2 .

It is a cyclic number.

It is not a de Polignac number, because 28040209 - 2²³ = 19651601 is a prime.

It is not a weakly prime, because it can be changed into another prime (28040239) 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, 14020104 + 14020105.

It is an arithmetic number, because the mean of its divisors is an integer number (14020105).

Almost surely, 2^28040209 is an apocalyptic number.

It is an amenable number.

28040209 is a deficient number, since it is larger than the sum of its proper divisors (1).

28040209 is an equidigital number, since it uses as much as digits as its factorization.

28040209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 28040209 is about 5295.3006524654. The cubic root of 28040209 is about 303.8041826718.

The spelling of 28040209 in words is "twenty-eight million, forty thousand, two hundred nine".