21212131111 has 2 divisors, whose sum is σ = 21212131112. Its totient is φ = 21212131110.

The previous prime is 21212131093. The next prime is 21212131153. The reversal of 21212131111 is 11113121212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21212131111 - 2⁷ = 21212130983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212131511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606065555 + 10606065556.

It is an arithmetic number, because the mean of its divisors is an integer number (10606065556).

Almost surely, 2^21212131111 is an apocalyptic number.

21212131111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212131111 is an equidigital number, since it uses as much as digits as its factorization.

21212131111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24, while the sum is 16.

Adding to 21212131111 its reverse (11113121212), we get a palindrome (32325252323).

The spelling of 21212131111 in words is "twenty-one billion, two hundred twelve million, one hundred thirty-one thousand, one hundred eleven".