21131123231 has 8 divisors (see below), whose sum is σ = 21471771600. Its totient is φ = 20793126208.

The previous prime is 21131123173. The next prime is 21131123297. The reversal of 21131123231 is 13232113112.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21131123231 is a prime.

It is a super-2 number, since 2×21131123231² (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 (21131122231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 646766 + ... + 678651.

It is an arithmetic number, because the mean of its divisors is an integer number (2683971450).

Almost surely, 2^21131123231 is an apocalyptic number.

21131123231 is a deficient number, since it is larger than the sum of its proper divisors (340648369).

21131123231 is a wasteful number, since it uses less digits than its factorization.

21131123231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325673.

The product of its digits is 216, while the sum is 20.

Adding to 21131123231 its reverse (13232113112), we get a palindrome (34363236343).

The spelling of 21131123231 in words is "twenty-one billion, one hundred thirty-one million, one hundred twenty-three thousand, two hundred thirty-one".