21155435393 has 2 divisors, whose sum is σ = 21155435394. Its totient is φ = 21155435392.

The previous prime is 21155435383. The next prime is 21155435419. The reversal of 21155435393 is 39353455112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20534030209 + 621405184 = 143297^2 + 24928^2 .

It is a cyclic number.

It is not a de Polignac number, because 21155435393 - 2²⁸ = 20886999937 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21155435393.

It is not a weakly prime, because it can be changed into another prime (21155435383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577717696 + 10577717697.

It is an arithmetic number, because the mean of its divisors is an integer number (10577717697).

Almost surely, 2^21155435393 is an apocalyptic number.

It is an amenable number.

21155435393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21155435393 is an equidigital number, since it uses as much as digits as its factorization.

21155435393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 243000, while the sum is 41.

The spelling of 21155435393 in words is "twenty-one billion, one hundred fifty-five million, four hundred thirty-five thousand, three hundred ninety-three".