171999 has 12 divisors (see below), whose sum is σ = 257400. Its totient is φ = 110544.

The previous prime is 171947. The next prime is 172001. The reversal of 171999 is 999171.

It is not a de Polignac number, because 171999 - 2¹¹ = 169951 is a prime.

171999 is a modest number, since divided by 999 gives 171 as remainder.

171999 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171929) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 69 + ... + 590.

It is an arithmetic number, because the mean of its divisors is an integer number (21450).

2¹⁷¹⁹⁹⁹ is an apocalyptic number.

171999 is a deficient number, since it is larger than the sum of its proper divisors (85401).

171999 is a wasteful number, since it uses less digits than its factorization.

171999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694 (or 691 counting only the distinct ones).

The product of its digits is 5103, while the sum is 36.

The square root of 171999 is about 414.7276214577. The cubic root of 171999 is about 55.6128698879.

It can be divided in two parts, 17 and 1999, that added together give a triangular number (2016 = T₆₃).

The spelling of 171999 in words is "one hundred seventy-one thousand, nine hundred ninety-nine".