21211123111 has 4 divisors (see below), whose sum is σ = 21218764032. Its totient is φ = 21203482192.

The previous prime is 21211123103. The next prime is 21211123139. The reversal of 21211123111 is 11132111212.

It is a happy number.

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 21211123111 - 2³ = 21211123103 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211123811) 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, 3816295 + ... + 3821848.

It is an arithmetic number, because the mean of its divisors is an integer number (5304691008).

Almost surely, 2^21211123111 is an apocalyptic number.

21211123111 is a deficient number, since it is larger than the sum of its proper divisors (7640921).

21211123111 is an equidigital number, since it uses as much as digits as its factorization.

21211123111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7640920.

The product of its digits is 24, while the sum is 16.

Adding to 21211123111 its reverse (11132111212), we get a palindrome (32343234323).

The spelling of 21211123111 in words is "twenty-one billion, two hundred eleven million, one hundred twenty-three thousand, one hundred eleven".