21131222111 has 2 divisors, whose sum is σ = 21131222112. Its totient is φ = 21131222110.

The previous prime is 21131222069. The next prime is 21131222129. The reversal of 21131222111 is 11122213112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21131222111 - 2¹⁰ = 21131221087 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21131222111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21131222011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565611055 + 10565611056.

It is an arithmetic number, because the mean of its divisors is an integer number (10565611056).

Almost surely, 2^21131222111 is an apocalyptic number.

21131222111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21131222111 is an equidigital number, since it uses as much as digits as its factorization.

21131222111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48, while the sum is 17.

Adding to 21131222111 its reverse (11122213112), we get a palindrome (32253435223).

The spelling of 21131222111 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-two thousand, one hundred eleven".