166864391 has 2 divisors, whose sum is σ = 166864392. Its totient is φ = 166864390.

The previous prime is 166864363. The next prime is 166864421. The reversal of 166864391 is 193468661.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166864391 - 2¹⁴ = 166848007 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166864091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83432195 + 83432196.

It is an arithmetic number, because the mean of its divisors is an integer number (83432196).

Almost surely, 2^166864391 is an apocalyptic number.

166864391 is a deficient number, since it is larger than the sum of its proper divisors (1).

166864391 is an equidigital number, since it uses as much as digits as its factorization.

166864391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 186624, while the sum is 44.

The square root of 166864391 is about 12917.6000479965. The cubic root of 166864391 is about 550.5387459347.

The spelling of 166864391 in words is "one hundred sixty-six million, eight hundred sixty-four thousand, three hundred ninety-one".