171991089 has 6 divisors (see below), whose sum is σ = 248431586. Its totient is φ = 114660720.

The previous prime is 171991081. The next prime is 171991103. The reversal of 171991089 is 980199171.

It can be written as a sum of positive squares in only one way, i.e., 168350625 + 3640464 = 12975^2 + 1908^2 .

It is not a de Polignac number, because 171991089 - 2³ = 171991081 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (171991081) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9555052 + ... + 9555069.

Almost surely, 2^171991089 is an apocalyptic number.

It is an amenable number.

171991089 is a deficient number, since it is larger than the sum of its proper divisors (76440497).

171991089 is a wasteful number, since it uses less digits than its factorization.

171991089 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19110127 (or 19110124 counting only the distinct ones).

The product of its (nonzero) digits is 40824, while the sum is 45.

The square root of 171991089 is about 13114.5373155137. The cubic root of 171991089 is about 556.1201724699.

The spelling of 171991089 in words is "one hundred seventy-one million, nine hundred ninety-one thousand, eighty-nine".