171991001 has 16 divisors (see below), whose sum is σ = 216190464. Its totient is φ = 133182144.

The previous prime is 171990977. The next prime is 171991003. The reversal of 171991001 is 100199171.

171991001 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 171991001 - 2⁶ = 171990937 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (171991003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15830 + ... + 24383.

It is an arithmetic number, because the mean of its divisors is an integer number (13511904).

Almost surely, 2^171991001 is an apocalyptic number.

It is an amenable number.

171991001 is a deficient number, since it is larger than the sum of its proper divisors (44199463).

171991001 is a wasteful number, since it uses less digits than its factorization.

171991001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40280.

The product of its (nonzero) digits is 567, while the sum is 29.

The square root of 171991001 is about 13114.5339604578. The cubic root of 171991001 is about 556.1200776228.

The spelling of 171991001 in words is "one hundred seventy-one million, nine hundred ninety-one thousand, one".