20111121209 has 2 divisors, whose sum is σ = 20111121210. Its totient is φ = 20111121208.

The previous prime is 20111121187. The next prime is 20111121211. The reversal of 20111121209 is 90212111102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19984063225 + 127057984 = 141365^2 + 11272^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20111121209 is a prime.

Together with 20111121211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20111121299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10055560604 + 10055560605.

It is an arithmetic number, because the mean of its divisors is an integer number (10055560605).

Almost surely, 2^20111121209 is an apocalyptic number.

It is an amenable number.

20111121209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20111121209 is an equidigital number, since it uses as much as digits as its factorization.

20111121209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 20.

The spelling of 20111121209 in words is "twenty billion, one hundred eleven million, one hundred twenty-one thousand, two hundred nine".