1666320267971 has 4 divisors (see below), whose sum is σ = 1666939030512. Its totient is φ = 1665701505432.

The previous prime is 1666320267967. The next prime is 1666320268007. The reversal of 1666320267971 is 1797620236661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1666320267971 - 2² = 1666320267967 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666320267071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 309377231 + ... + 309382616.

It is an arithmetic number, because the mean of its divisors is an integer number (416734757628).

Almost surely, 2^{1666320267971} is an apocalyptic number.

1666320267971 is a deficient number, since it is larger than the sum of its proper divisors (618762541).

1666320267971 is an equidigital number, since it uses as much as digits as its factorization.

1666320267971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618762540.

The product of its (nonzero) digits is 6858432, while the sum is 56.

The spelling of 1666320267971 in words is "one trillion, six hundred sixty-six billion, three hundred twenty million, two hundred sixty-seven thousand, nine hundred seventy-one".