1666609705571 has 2 divisors, whose sum is σ = 1666609705572. Its totient is φ = 1666609705570.

The previous prime is 1666609705517. The next prime is 1666609705589. The reversal of 1666609705571 is 1755079066661.

Together with previous prime (1666609705517) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1666609705571 - 2²² = 1666605511267 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1666609705571.

It is not a weakly prime, because it can be changed into another prime (1666609705171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833304852785 + 833304852786.

It is an arithmetic number, because the mean of its divisors is an integer number (833304852786).

Almost surely, 2^{1666609705571} is an apocalyptic number.

1666609705571 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666609705571 is an equidigital number, since it uses as much as digits as its factorization.

1666609705571 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14288400, while the sum is 59.

The spelling of 1666609705571 in words is "one trillion, six hundred sixty-six billion, six hundred nine million, seven hundred five thousand, five hundred seventy-one".