21212121111011 has 4 divisors (see below), whose sum is σ = 21364726299000. Its totient is φ = 21059515923024.

The previous prime is 21212121110981. The next prime is 21212121111059. The reversal of 21212121111011 is 11011112121212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21212121111011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212121111611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76302593786 + ... + 76302594063.

It is an arithmetic number, because the mean of its divisors is an integer number (5341181574750).

Almost surely, 2^{21212121111011} is an apocalyptic number.

21212121111011 is a deficient number, since it is larger than the sum of its proper divisors (152605187989).

21212121111011 is a wasteful number, since it uses less digits than its factorization.

21212121111011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152605187988.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 21212121111011 its reverse (11011112121212), we get a palindrome (32223233232223).

The spelling of 21212121111011 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty-one million, one hundred eleven thousand, eleven".