21131223111 has 8 divisors (see below), whose sum is σ = 31305515760. Its totient is φ = 14087482056.

The previous prime is 21131223101. The next prime is 21131223161. The reversal of 21131223111 is 11132213112.

It is not a de Polignac number, because 21131223111 - 2⁵ = 21131223079 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131223101) 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, 391318920 + ... + 391318973.

It is an arithmetic number, because the mean of its divisors is an integer number (3913189470).

Almost surely, 2^21131223111 is an apocalyptic number.

21131223111 is a deficient number, since it is larger than the sum of its proper divisors (10174292649).

21131223111 is an equidigital number, since it uses as much as digits as its factorization.

21131223111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782637902 (or 782637896 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 21131223111 its reverse (11132213112), we get a palindrome (32263436223).

Subtracting from 21131223111 its reverse (11132213112), we obtain a palindrome (9999009999).

The spelling of 21131223111 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-three thousand, one hundred eleven".