21320111231 has 4 divisors (see below), whose sum is σ = 21320413464. Its totient is φ = 21319809000.

The previous prime is 21320111227. The next prime is 21320111237. The reversal of 21320111231 is 13211102312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21320111231 - 2² = 21320111227 is a prime.

It is a super-2 number, since 2×21320111231² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320111237) 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, 17156 + ... + 207206.

It is an arithmetic number, because the mean of its divisors is an integer number (5330103366).

Almost surely, 2^21320111231 is an apocalyptic number.

21320111231 is a deficient number, since it is larger than the sum of its proper divisors (302233).

21320111231 is a wasteful number, since it uses less digits than its factorization.

21320111231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302232.

The product of its (nonzero) digits is 72, while the sum is 17.

Adding to 21320111231 its reverse (13211102312), we get a palindrome (34531213543).

The spelling of 21320111231 in words is "twenty-one billion, three hundred twenty million, one hundred eleven thousand, two hundred thirty-one".