171991747812 has 24 divisors (see below), whose sum is σ = 424920789216. Its totient is φ = 53958195328.

The previous prime is 171991747751. The next prime is 171991747813. The reversal of 171991747812 is 218747199171.

It is a happy number.

It is a super-2 number, since 2×171991747812² (a number of 23 digits) contains 22 as substring.

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, 421548198 + ... + 421548605.

It is an arithmetic number, because the mean of its divisors is an integer number (17705032884).

Almost surely, 2^171991747812 is an apocalyptic number.

171991747812 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

171991747812 is an abundant number, since it is smaller than the sum of its proper divisors (252929041404).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

171991747812 is a wasteful number, since it uses less digits than its factorization.

171991747812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 843096827 (or 843096825 counting only the distinct ones).

The product of its digits is 1778112, while the sum is 57.

The spelling of 171991747812 in words is "one hundred seventy-one billion, nine hundred ninety-one million, seven hundred forty-seven thousand, eight hundred twelve".