1666686739 has 2 divisors, whose sum is σ = 1666686740. Its totient is φ = 1666686738.

The previous prime is 1666686701. The next prime is 1666686803. The reversal of 1666686739 is 9376866661.

It is a weak prime.

It is an emirp because it is prime and its reverse (9376866661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666686739 - 2⁹ = 1666686227 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666684739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833343369 + 833343370.

It is an arithmetic number, because the mean of its divisors is an integer number (833343370).

Almost surely, 2^1666686739 is an apocalyptic number.

1666686739 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666686739 is an equidigital number, since it uses as much as digits as its factorization.

1666686739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11757312, while the sum is 58.

The square root of 1666686739 is about 40825.0748805192. The cubic root of 1666686739 is about 1185.6358611541.

The spelling of 1666686739 in words is "one billion, six hundred sixty-six million, six hundred eighty-six thousand, seven hundred thirty-nine".