18664977691 has 2 divisors, whose sum is σ = 18664977692. Its totient is φ = 18664977690.

The previous prime is 18664977649. The next prime is 18664977761. The reversal of 18664977691 is 19677946681.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18664977691 - 2⁹ = 18664977179 is a prime.

It is not a weakly prime, because it can be changed into another prime (18664977491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9332488845 + 9332488846.

It is an arithmetic number, because the mean of its divisors is an integer number (9332488846).

Almost surely, 2^18664977691 is an apocalyptic number.

18664977691 is a deficient number, since it is larger than the sum of its proper divisors (1).

18664977691 is an equidigital number, since it uses as much as digits as its factorization.

18664977691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27433728, while the sum is 64.

The spelling of 18664977691 in words is "eighteen billion, six hundred sixty-four million, nine hundred seventy-seven thousand, six hundred ninety-one".