171664391 has 12 divisors (see below), whose sum is σ = 179883936. Its totient is φ = 163784160.

The previous prime is 171664327. The next prime is 171664447. The reversal of 171664391 is 193466171.

It is a happy number.

It is not a de Polignac number, because 171664391 - 2⁶ = 171664327 is a prime.

It is a super-3 number, since 3×171664391³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171664301) 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 in 11 ways as a sum of consecutive naturals, for example, 68930 + ... + 71376.

It is an arithmetic number, because the mean of its divisors is an integer number (14990328).

Almost surely, 2^171664391 is an apocalyptic number.

171664391 is a deficient number, since it is larger than the sum of its proper divisors (8219545).

171664391 is an equidigital number, since it uses as much as digits as its factorization.

171664391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2582 (or 2551 counting only the distinct ones).

The product of its digits is 27216, while the sum is 38.

The square root of 171664391 is about 13102.0758278984. The cubic root of 171664391 is about 555.7678315301.

The spelling of 171664391 in words is "one hundred seventy-one million, six hundred sixty-four thousand, three hundred ninety-one".