21211122111 has 8 divisors (see below), whose sum is σ = 28288095024. Its totient is φ = 14137448640.

The previous prime is 21211122073. The next prime is 21211122151. The reversal of 21211122111 is 11122111212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21211122111 - 2⁷ = 21211121983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211122151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 809820 + ... + 835601.

It is an arithmetic number, because the mean of its divisors is an integer number (3536011878).

Almost surely, 2^21211122111 is an apocalyptic number.

21211122111 is a deficient number, since it is larger than the sum of its proper divisors (7076972913).

21211122111 is a wasteful number, since it uses less digits than its factorization.

21211122111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1649721.

The product of its digits is 16, while the sum is 15.

Adding to 21211122111 its reverse (11122111212), we get a palindrome (32333233323).

It can be divided in two parts, 212 and 11122111, that multiplied together give a palindrome (2357887532).

The spelling of 21211122111 in words is "twenty-one billion, two hundred eleven million, one hundred twenty-two thousand, one hundred eleven".