31819781161 has 27 divisors (see below), whose sum is σ = 39346518999. Its totient is φ = 25652614848.

The previous prime is 31819781153. The next prime is 31819781237. The reversal of 31819781161 is 16118791813.

The square root of 31819781161 is 178381.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 24773186025 + 7046595136 = 157395^2 + 83944^2 .

It is not a de Polignac number, because 31819781161 - 2³ = 31819781153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31819761161) 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 26 ways as a sum of consecutive naturals, for example, 21226590 + ... + 21228088.

Almost surely, 2^31819781161 is an apocalyptic number.

31819781161 is the 178381-st square number.

31819781161 is the 89191-st centered octagonal number.

It is an amenable number.

31819781161 is a deficient number, since it is larger than the sum of its proper divisors (7526737838).

31819781161 is an frugal number, since it uses more digits than its factorization.

31819781161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3046 (or 1523 counting only the distinct ones).

The product of its digits is 72576, while the sum is 46.

The spelling of 31819781161 in words is "thirty-one billion, eight hundred nineteen million, seven hundred eighty-one thousand, one hundred sixty-one".