21111431321 has 2 divisors, whose sum is σ = 21111431322. Its totient is φ = 21111431320.

The previous prime is 21111431293. The next prime is 21111431323. The reversal of 21111431321 is 12313411112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13373766025 + 7737665296 = 115645^2 + 87964^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111431321 - 2²² = 21107237017 is a prime.

Together with 21111431323, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21111431293 and 21111431302.

It is not a weakly prime, because it can be changed into another prime (21111431323) 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 as a sum of consecutive naturals, namely, 10555715660 + 10555715661.

It is an arithmetic number, because the mean of its divisors is an integer number (10555715661).

Almost surely, 2^21111431321 is an apocalyptic number.

It is an amenable number.

21111431321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111431321 is an equidigital number, since it uses as much as digits as its factorization.

21111431321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 20.

Adding to 21111431321 its reverse (12313411112), we get a palindrome (33424842433).

The spelling of 21111431321 in words is "twenty-one billion, one hundred eleven million, four hundred thirty-one thousand, three hundred twenty-one".