21124213393 has 2 divisors, whose sum is σ = 21124213394. Its totient is φ = 21124213392.

The previous prime is 21124213391. The next prime is 21124213421. The reversal of 21124213393 is 39331242112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17813707024 + 3310506369 = 133468^2 + 57537^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124213393 - 2¹ = 21124213391 is a prime.

Together with 21124213391, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21124213391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562106696 + 10562106697.

It is an arithmetic number, because the mean of its divisors is an integer number (10562106697).

Almost surely, 2^21124213393 is an apocalyptic number.

It is an amenable number.

21124213393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124213393 is an equidigital number, since it uses as much as digits as its factorization.

21124213393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 31.

The spelling of 21124213393 in words is "twenty-one billion, one hundred twenty-four million, two hundred thirteen thousand, three hundred ninety-three".