171991747811 has 8 divisors (see below), whose sum is σ = 186358215120. Its totient is φ = 157787613792.

The previous prime is 171991747751. The next prime is 171991747813. The reversal of 171991747811 is 118747199171.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 171991747811 - 2²⁶ = 171924638947 is a prime.

It is a super-2 number, since 2×171991747811² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (171991747813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40581116 + ... + 40585353.

It is an arithmetic number, because the mean of its divisors is an integer number (23294776890).

Almost surely, 2^171991747811 is an apocalyptic number.

171991747811 is a deficient number, since it is larger than the sum of its proper divisors (14366467309).

171991747811 is a wasteful number, since it uses less digits than its factorization.

171991747811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81166645.

The product of its digits is 889056, while the sum is 56.

The spelling of 171991747811 in words is "one hundred seventy-one billion, nine hundred ninety-one million, seven hundred forty-seven thousand, eight hundred eleven".