8121209 has 2 divisors, whose sum is σ = 8121210. Its totient is φ = 8121208.

The previous prime is 8121199. The next prime is 8121283. The reversal of 8121209 is 9021218.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6775609 + 1345600 = 2603^2 + 1160^2 .

It is a cyclic number.

It is not a de Polignac number, because 8121209 - 2⁸ = 8120953 is a prime.

It is not a weakly prime, because it can be changed into another prime (8121299) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4060604 + 4060605.

It is an arithmetic number, because the mean of its divisors is an integer number (4060605).

Almost surely, 2^8121209 is an apocalyptic number.

It is an amenable number.

8121209 is a deficient number, since it is larger than the sum of its proper divisors (1).

8121209 is an equidigital number, since it uses as much as digits as its factorization.

8121209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 8121209 is about 2849.7734997715. The cubic root of 8121209 is about 201.0050162523.

Subtracting 8121209 from its reverse (9021218), we obtain a palindrome (900009).

The spelling of 8121209 in words is "eight million, one hundred twenty-one thousand, two hundred nine".