666731693 has 2 divisors, whose sum is σ = 666731694. Its totient is φ = 666731692.

The previous prime is 666731657. The next prime is 666731701. The reversal of 666731693 is 396137666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 653211364 + 13520329 = 25558^2 + 3677^2 .

It is a cyclic number.

It is not a de Polignac number, because 666731693 - 2¹⁸ = 666469549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666734693) 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, 333365846 + 333365847.

It is an arithmetic number, because the mean of its divisors is an integer number (333365847).

Almost surely, 2^666731693 is an apocalyptic number.

It is an amenable number.

666731693 is a deficient number, since it is larger than the sum of its proper divisors (1).

666731693 is an equidigital number, since it uses as much as digits as its factorization.

666731693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 734832, while the sum is 47.

The square root of 666731693 is about 25821.1481735418. The cubic root of 666731693 is about 873.6088666801.

The spelling of 666731693 in words is "six hundred sixty-six million, seven hundred thirty-one thousand, six hundred ninety-three".