21120111209 has 2 divisors, whose sum is σ = 21120111210. Its totient is φ = 21120111208.

The previous prime is 21120111203. The next prime is 21120111227. The reversal of 21120111209 is 90211102112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14404800400 + 6715310809 = 120020^2 + 81947^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120111209 - 2³² = 16825143913 is a prime.

It is not a weakly prime, because it can be changed into another prime (21120111203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560055604 + 10560055605.

It is an arithmetic number, because the mean of its divisors is an integer number (10560055605).

Almost surely, 2^21120111209 is an apocalyptic number.

It is an amenable number.

21120111209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120111209 is an equidigital number, since it uses as much as digits as its factorization.

21120111209 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 21120111209 in words is "twenty-one billion, one hundred twenty million, one hundred eleven thousand, two hundred nine".