166805794591 has 2 divisors, whose sum is σ = 166805794592. Its totient is φ = 166805794590.

The previous prime is 166805794583. The next prime is 166805794657. The reversal of 166805794591 is 195497508661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166805794591 - 2³ = 166805794583 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166805794501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83402897295 + 83402897296.

It is an arithmetic number, because the mean of its divisors is an integer number (83402897296).

Almost surely, 2^166805794591 is an apocalyptic number.

166805794591 is a deficient number, since it is larger than the sum of its proper divisors (1).

166805794591 is an equidigital number, since it uses as much as digits as its factorization.

166805794591 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16329600, while the sum is 61.

The spelling of 166805794591 in words is "one hundred sixty-six billion, eight hundred five million, seven hundred ninety-four thousand, five hundred ninety-one".