21311233011209 has 2 divisors, whose sum is σ = 21311233011210. Its totient is φ = 21311233011208.

The previous prime is 21311233011197. The next prime is 21311233011223. The reversal of 21311233011209 is 90211033211312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15442227715600 + 5869005295609 = 3929660^2 + 2422603^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311233011209 is a prime.

It is not a weakly prime, because it can be changed into another prime (21311233011259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655616505604 + 10655616505605.

It is an arithmetic number, because the mean of its divisors is an integer number (10655616505605).

Almost surely, 2^{21311233011209} is an apocalyptic number.

It is an amenable number.

21311233011209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21311233011209 is an equidigital number, since it uses as much as digits as its factorization.

21311233011209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 29.

The spelling of 21311233011209 in words is "twenty-one trillion, three hundred eleven billion, two hundred thirty-three million, eleven thousand, two hundred nine".