18805542661 has 2 divisors, whose sum is σ = 18805542662. Its totient is φ = 18805542660.

The previous prime is 18805542659. The next prime is 18805542671. The reversal of 18805542661 is 16624550881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15374512036 + 3431030625 = 123994^2 + 58575^2 .

It is a cyclic number.

It is not a de Polignac number, because 18805542661 - 2¹ = 18805542659 is a prime.

Together with 18805542659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18805542631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9402771330 + 9402771331.

It is an arithmetic number, because the mean of its divisors is an integer number (9402771331).

Almost surely, 2^18805542661 is an apocalyptic number.

It is an amenable number.

18805542661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18805542661 is an equidigital number, since it uses as much as digits as its factorization.

18805542661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 460800, while the sum is 46.

The spelling of 18805542661 in words is "eighteen billion, eight hundred five million, five hundred forty-two thousand, six hundred sixty-one".