171373991 has 4 divisors (see below), whose sum is σ = 181454832. Its totient is φ = 161293152.

The previous prime is 171373967. The next prime is 171373999. The reversal of 171373991 is 199373171.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199373171 = 4397 ⋅45343.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-171373991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171373999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5040395 + ... + 5040428.

It is an arithmetic number, because the mean of its divisors is an integer number (45363708).

Almost surely, 2^171373991 is an apocalyptic number.

171373991 is a deficient number, since it is larger than the sum of its proper divisors (10080841).

171373991 is a wasteful number, since it uses less digits than its factorization.

171373991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10080840.

The product of its digits is 35721, while the sum is 41.

The square root of 171373991 is about 13090.9889236833. The cubic root of 171373991 is about 555.4542621829.

The spelling of 171373991 in words is "one hundred seventy-one million, three hundred seventy-three thousand, nine hundred ninety-one".