21031332431 has 4 divisors (see below), whose sum is σ = 21064143264. Its totient is φ = 20998521600.

The previous prime is 21031332403. The next prime is 21031332479. The reversal of 21031332431 is 13423313012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21031332431 is a prime.

It is a super-2 number, since 2×21031332431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031332397 and 21031332406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031332131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16404455 + ... + 16405736.

It is an arithmetic number, because the mean of its divisors is an integer number (5266035816).

Almost surely, 2^21031332431 is an apocalyptic number.

21031332431 is a deficient number, since it is larger than the sum of its proper divisors (32810833).

21031332431 is an equidigital number, since it uses as much as digits as its factorization.

21031332431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32810832.

The product of its (nonzero) digits is 1296, while the sum is 23.

Adding to 21031332431 its reverse (13423313012), we get a palindrome (34454645443).

The spelling of 21031332431 in words is "twenty-one billion, thirty-one million, three hundred thirty-two thousand, four hundred thirty-one".