21786915911 has 2 divisors, whose sum is σ = 21786915912. Its totient is φ = 21786915910.

The previous prime is 21786915907. The next prime is 21786915923. The reversal of 21786915911 is 11951968712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21786915911 - 2² = 21786915907 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21786915911.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21786915211) 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, 10893457955 + 10893457956.

It is an arithmetic number, because the mean of its divisors is an integer number (10893457956).

Almost surely, 2^21786915911 is an apocalyptic number.

21786915911 is a deficient number, since it is larger than the sum of its proper divisors (1).

21786915911 is an equidigital number, since it uses as much as digits as its factorization.

21786915911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 272160, while the sum is 50.

The spelling of 21786915911 in words is "twenty-one billion, seven hundred eighty-six million, nine hundred fifteen thousand, nine hundred eleven".