19666066691 has 2 divisors, whose sum is σ = 19666066692. Its totient is φ = 19666066690.

The previous prime is 19666066681. The next prime is 19666066709.

19666066691 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 19666066691 - 2⁶ = 19666066627 is a prime.

It is not a weakly prime, because it can be changed into another prime (19666066621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9833033345 + 9833033346.

It is an arithmetic number, because the mean of its divisors is an integer number (9833033346).

Almost surely, 2^19666066691 is an apocalyptic number.

19666066691 is a deficient number, since it is larger than the sum of its proper divisors (1).

19666066691 is an equidigital number, since it uses as much as digits as its factorization.

19666066691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3779136, while the sum is 56.

The spelling of 19666066691 in words is "nineteen billion, six hundred sixty-six million, sixty-six thousand, six hundred ninety-one".