21231231211 has 2 divisors, whose sum is σ = 21231231212. Its totient is φ = 21231231210.

The previous prime is 21231231193. The next prime is 21231231221. The reversal of 21231231211 is 11213213212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21231231211 - 2⁷ = 21231231083 is a prime.

It is not a weakly prime, because it can be changed into another prime (21231231221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615615605 + 10615615606.

It is an arithmetic number, because the mean of its divisors is an integer number (10615615606).

Almost surely, 2^21231231211 is an apocalyptic number.

21231231211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231231211 is an equidigital number, since it uses as much as digits as its factorization.

21231231211 is an evil number, because the sum of its binary digits is even.

The product of its digits is 144, while the sum is 19.

Adding to 21231231211 its reverse (11213213212), we get a palindrome (32444444423).

The spelling of 21231231211 in words is "twenty-one billion, two hundred thirty-one million, two hundred thirty-one thousand, two hundred eleven".