21201211111 has 2 divisors, whose sum is σ = 21201211112. Its totient is φ = 21201211110.

The previous prime is 21201211093. The next prime is 21201211133. The reversal of 21201211111 is 11111210212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21201211111 - 2⁹ = 21201210599 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201211091 and 21201211100.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201211181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600605555 + 10600605556.

It is an arithmetic number, because the mean of its divisors is an integer number (10600605556).

Almost surely, 2^21201211111 is an apocalyptic number.

21201211111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201211111 is an equidigital number, since it uses as much as digits as its factorization.

21201211111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21201211111 its reverse (11111210212), we get a palindrome (32312421323).

The spelling of 21201211111 in words is "twenty-one billion, two hundred one million, two hundred eleven thousand, one hundred eleven".