21242431393 has 2 divisors, whose sum is σ = 21242431394. Its totient is φ = 21242431392.

The previous prime is 21242431391. The next prime is 21242431417. The reversal of 21242431393 is 39313424212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11026680064 + 10215751329 = 105008^2 + 101073^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242431393 - 2¹ = 21242431391 is a prime.

Together with 21242431391, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21242431391) 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, 10621215696 + 10621215697.

It is an arithmetic number, because the mean of its divisors is an integer number (10621215697).

Almost surely, 2^21242431393 is an apocalyptic number.

It is an amenable number.

21242431393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21242431393 is an equidigital number, since it uses as much as digits as its factorization.

21242431393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 34.

The spelling of 21242431393 in words is "twenty-one billion, two hundred forty-two million, four hundred thirty-one thousand, three hundred ninety-three".