161731178772 has 48 divisors (see below), whose sum is σ = 386987063232. Its totient is φ = 52542362880.

The previous prime is 161731178753. The next prime is 161731178773. The reversal of 161731178772 is 277871137161.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161731178773) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 102073 + ... + 577824.

It is an arithmetic number, because the mean of its divisors is an integer number (8062230484).

Almost surely, 2^161731178772 is an apocalyptic number.

161731178772 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

161731178772 is an abundant number, since it is smaller than the sum of its proper divisors (225255884460).

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

161731178772 is a wasteful number, since it uses less digits than its factorization.

161731178772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680408 (or 680406 counting only the distinct ones).

The product of its digits is 691488, while the sum is 51.

The spelling of 161731178772 in words is "one hundred sixty-one billion, seven hundred thirty-one million, one hundred seventy-eight thousand, seven hundred seventy-two".