21312131011 has 4 divisors (see below), whose sum is σ = 21312423000. Its totient is φ = 21311839024.

The previous prime is 21312130999. The next prime is 21312131047. The reversal of 21312131011 is 11013121312.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-21312131011 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21312131051) 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, 70815 + ... + 218263.

It is an arithmetic number, because the mean of its divisors is an integer number (5328105750).

Almost surely, 2^21312131011 is an apocalyptic number.

21312131011 is a deficient number, since it is larger than the sum of its proper divisors (291989).

21312131011 is a wasteful number, since it uses less digits than its factorization.

21312131011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291988.

The product of its (nonzero) digits is 36, while the sum is 16.

Adding to 21312131011 its reverse (11013121312), we get a palindrome (32325252323).

The spelling of 21312131011 in words is "twenty-one billion, three hundred twelve million, one hundred thirty-one thousand, eleven".