21040031393 has 2 divisors, whose sum is σ = 21040031394. Its totient is φ = 21040031392.

The previous prime is 21040031323. The next prime is 21040031429. The reversal of 21040031393 is 39313004012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16132048144 + 4907983249 = 127012^2 + 70057^2 .

It is a cyclic number.

It is not a de Polignac number, because 21040031393 - 2¹⁰ = 21040030369 is a prime.

It is not a weakly prime, because it can be changed into another prime (21040031323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520015696 + 10520015697.

It is an arithmetic number, because the mean of its divisors is an integer number (10520015697).

Almost surely, 2^21040031393 is an apocalyptic number.

It is an amenable number.

21040031393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040031393 is an equidigital number, since it uses as much as digits as its factorization.

21040031393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 26.

The spelling of 21040031393 in words is "twenty-one billion, forty million, thirty-one thousand, three hundred ninety-three".