166681393 has 2 divisors, whose sum is σ = 166681394. Its totient is φ = 166681392.

The previous prime is 166681381. The next prime is 166681397. The reversal of 166681393 is 393186661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 163021824 + 3659569 = 12768^2 + 1913^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166681393 is a prime.

It is not a weakly prime, because it can be changed into another prime (166681397) 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, 83340696 + 83340697.

It is an arithmetic number, because the mean of its divisors is an integer number (83340697).

Almost surely, 2^166681393 is an apocalyptic number.

It is an amenable number.

166681393 is a deficient number, since it is larger than the sum of its proper divisors (1).

166681393 is an equidigital number, since it uses as much as digits as its factorization.

166681393 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 43.

The square root of 166681393 is about 12910.5148231974. The cubic root of 166681393 is about 550.3374160988.

The spelling of 166681393 in words is "one hundred sixty-six million, six hundred eighty-one thousand, three hundred ninety-three".