21212111011211 has 4 divisors (see below), whose sum is σ = 21215864708424. Its totient is φ = 21208357314000.

The previous prime is 21212111011199. The next prime is 21212111011229. The reversal of 21212111011211 is 11211011121212.

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

It is a cyclic number.

It is not a de Polignac number, because 21212111011211 - 2²² = 21212106816907 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21212111011211.

It is not an unprimeable number, because it can be changed into a prime (21212111011261) 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, 1876840130 + ... + 1876851431.

It is an arithmetic number, because the mean of its divisors is an integer number (5303966177106).

Almost surely, 2^{21212111011211} is an apocalyptic number.

21212111011211 is a deficient number, since it is larger than the sum of its proper divisors (3753697213).

21212111011211 is an equidigital number, since it uses as much as digits as its factorization.

21212111011211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3753697212.

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

Adding to 21212111011211 its reverse (11211011121212), we get a palindrome (32423122132423).

The spelling of 21212111011211 in words is "twenty-one trillion, two hundred twelve billion, one hundred eleven million, eleven thousand, two hundred eleven".