6665221571 has 2 divisors, whose sum is σ = 6665221572. Its totient is φ = 6665221570.

The previous prime is 6665221517. The next prime is 6665221627. The reversal of 6665221571 is 1751225666.

Together with previous prime (6665221517) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6665221571 is a prime.

It is not a weakly prime, because it can be changed into another prime (6665221471) 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 as a sum of consecutive naturals, namely, 3332610785 + 3332610786.

It is an arithmetic number, because the mean of its divisors is an integer number (3332610786).

Almost surely, 2^6665221571 is an apocalyptic number.

6665221571 is a deficient number, since it is larger than the sum of its proper divisors (1).

6665221571 is an equidigital number, since it uses as much as digits as its factorization.

6665221571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 151200, while the sum is 41.

The square root of 6665221571 is about 81640.8082456317. The cubic root of 6665221571 is about 1881.9360592263.

The spelling of 6665221571 in words is "six billion, six hundred sixty-five million, two hundred twenty-one thousand, five hundred seventy-one".