21644693263 has 2 divisors, whose sum is σ = 21644693264. Its totient is φ = 21644693262.

The previous prime is 21644693251. The next prime is 21644693269. The reversal of 21644693263 is 36239644612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21644693263 - 2²¹ = 21642596111 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21644693269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822346631 + 10822346632.

It is an arithmetic number, because the mean of its divisors is an integer number (10822346632).

Almost surely, 2^21644693263 is an apocalyptic number.

21644693263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644693263 is an equidigital number, since it uses as much as digits as its factorization.

21644693263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1119744, while the sum is 46.

The spelling of 21644693263 in words is "twenty-one billion, six hundred forty-four million, six hundred ninety-three thousand, two hundred sixty-three".