1666663771 has 2 divisors, whose sum is σ = 1666663772. Its totient is φ = 1666663770.

The previous prime is 1666663769. The next prime is 1666663807. The reversal of 1666663771 is 1773666661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666663771 - 2¹ = 1666663769 is a prime.

Together with 1666663769, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1666663171) 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, 833331885 + 833331886.

It is an arithmetic number, because the mean of its divisors is an integer number (833331886).

Almost surely, 2^1666663771 is an apocalyptic number.

1666663771 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666663771 is an equidigital number, since it uses as much as digits as its factorization.

1666663771 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 49.

The square root of 1666663771 is about 40824.7935818419. The cubic root of 1666663771 is about 1185.6304148578.

The spelling of 1666663771 in words is "one billion, six hundred sixty-six million, six hundred sixty-three thousand, seven hundred seventy-one".