166561660663 has 2 divisors, whose sum is σ = 166561660664. Its totient is φ = 166561660662.

The previous prime is 166561660651. The next prime is 166561660669. The reversal of 166561660663 is 366066165661.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 166561660663 - 2⁹ = 166561660151 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 166561660663.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166561660669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83280830331 + 83280830332.

It is an arithmetic number, because the mean of its divisors is an integer number (83280830332).

Almost surely, 2^166561660663 is an apocalyptic number.

166561660663 is a deficient number, since it is larger than the sum of its proper divisors (1).

166561660663 is an equidigital number, since it uses as much as digits as its factorization.

166561660663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4199040, while the sum is 52.

The spelling of 166561660663 in words is "one hundred sixty-six billion, five hundred sixty-one million, six hundred sixty thousand, six hundred sixty-three".