21865644263 has 2 divisors, whose sum is σ = 21865644264. Its totient is φ = 21865644262.

The previous prime is 21865644193. The next prime is 21865644293. The reversal of 21865644263 is 36244656812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21865644263 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21865644293) 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, 10932822131 + 10932822132.

It is an arithmetic number, because the mean of its divisors is an integer number (10932822132).

Almost surely, 2^21865644263 is an apocalyptic number.

21865644263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21865644263 is an equidigital number, since it uses as much as digits as its factorization.

21865644263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1658880, while the sum is 47.

The spelling of 21865644263 in words is "twenty-one billion, eight hundred sixty-five million, six hundred forty-four thousand, two hundred sixty-three".