166868561 has 2 divisors, whose sum is σ = 166868562. Its totient is φ = 166868560.

The previous prime is 166868497. The next prime is 166868573. The reversal of 166868561 is 165868661.

166868561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 158130625 + 8737936 = 12575^2 + 2956^2 .

It is a cyclic number.

It is not a de Polignac number, because 166868561 - 2⁶ = 166868497 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (166808561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83434280 + 83434281.

It is an arithmetic number, because the mean of its divisors is an integer number (83434281).

Almost surely, 2^166868561 is an apocalyptic number.

It is an amenable number.

166868561 is a deficient number, since it is larger than the sum of its proper divisors (1).

166868561 is an equidigital number, since it uses as much as digits as its factorization.

166868561 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 166868561 is about 12917.7614546794. The cubic root of 166868561 is about 550.5433319490.

The spelling of 166868561 in words is "one hundred sixty-six million, eight hundred sixty-eight thousand, five hundred sixty-one".