171661091 has 4 divisors (see below), whose sum is σ = 196184112. Its totient is φ = 147138072.

The previous prime is 171661081. The next prime is 171661097. The reversal of 171661091 is 190166171.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190166171 = 13 ⋅14628167.

It is a cyclic number.

It is not a de Polignac number, because 171661091 - 2⁶ = 171661027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (171661097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12261500 + ... + 12261513.

It is an arithmetic number, because the mean of its divisors is an integer number (49046028).

Almost surely, 2^171661091 is an apocalyptic number.

171661091 is a deficient number, since it is larger than the sum of its proper divisors (24523021).

171661091 is an equidigital number, since it uses as much as digits as its factorization.

171661091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24523020.

The product of its (nonzero) digits is 2268, while the sum is 32.

The square root of 171661091 is about 13101.9498930503. The cubic root of 171661091 is about 555.7642702293.

The spelling of 171661091 in words is "one hundred seventy-one million, six hundred sixty-one thousand, ninety-one".