166568681 has 2 divisors, whose sum is σ = 166568682. Its totient is φ = 166568680.

The previous prime is 166568641. The next prime is 166568729. The reversal of 166568681 is 186865661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 129163225 + 37405456 = 11365^2 + 6116^2 .

It is an emirp because it is prime and its reverse (186865661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166568681 - 2¹⁰ = 166567657 is a prime.

It is a super-2 number, since 2×166568681² = 55490250980159522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (166568641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83284340 + 83284341.

It is an arithmetic number, because the mean of its divisors is an integer number (83284341).

Almost surely, 2^166568681 is an apocalyptic number.

It is an amenable number.

166568681 is a deficient number, since it is larger than the sum of its proper divisors (1).

166568681 is an equidigital number, since it uses as much as digits as its factorization.

166568681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 414720, while the sum is 47.

The square root of 166568681 is about 12906.1489608636. The cubic root of 166568681 is about 550.2133398263.

The spelling of 166568681 in words is "one hundred sixty-six million, five hundred sixty-eight thousand, six hundred eighty-one".