21111220211 has 4 divisors (see below), whose sum is σ = 22353056712. Its totient is φ = 19869383712.

The previous prime is 21111220199. The next prime is 21111220223. The reversal of 21111220211 is 11202211112.

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

It is an interprime number because it is at equal distance from previous prime (21111220199) and next prime (21111220223).

It is a cyclic number.

It is not a de Polignac number, because 21111220211 - 2¹⁰ = 21111219187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111220111) 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, 620918225 + ... + 620918258.

It is an arithmetic number, because the mean of its divisors is an integer number (5588264178).

Almost surely, 2^21111220211 is an apocalyptic number.

21111220211 is a deficient number, since it is larger than the sum of its proper divisors (1241836501).

21111220211 is a wasteful number, since it uses less digits than its factorization.

21111220211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241836500.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21111220211 its reverse (11202211112), we get a palindrome (32313431323).

Subtracting from 21111220211 its reverse (11202211112), we obtain a palindrome (9909009099).

The spelling of 21111220211 in words is "twenty-one billion, one hundred eleven million, two hundred twenty thousand, two hundred eleven".