21811332861 has 8 divisors (see below), whose sum is σ = 32313085760. Its totient is φ = 14540888556.

The previous prime is 21811332847. The next prime is 21811332887. The reversal of 21811332861 is 16823311812.

21811332861 is a `hidden beast` number, since 218 + 113 + 328 + 6 + 1 = 666.

It is not a de Polignac number, because 21811332861 - 2¹⁸ = 21811070717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21811332161) 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 in 7 ways as a sum of consecutive naturals, for example, 403913545 + ... + 403913598.

It is an arithmetic number, because the mean of its divisors is an integer number (4039135720).

Almost surely, 2^21811332861 is an apocalyptic number.

It is an amenable number.

21811332861 is a deficient number, since it is larger than the sum of its proper divisors (10501752899).

21811332861 is an equidigital number, since it uses as much as digits as its factorization.

21811332861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 807827152 (or 807827146 counting only the distinct ones).

The product of its digits is 13824, while the sum is 36.

The spelling of 21811332861 in words is "twenty-one billion, eight hundred eleven million, three hundred thirty-two thousand, eight hundred sixty-one".