81531831112 has 8 divisors (see below), whose sum is σ = 152872183350. Its totient is φ = 40765915552.

The previous prime is 81531831109. The next prime is 81531831167. The reversal of 81531831112 is 21113813518.

It can be written as a sum of positive squares in only one way, i.e., 58654058596 + 22877772516 = 242186^2 + 151254^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5095739437 + ... + 5095739452.

Almost surely, 2^81531831112 is an apocalyptic number.

It is an amenable number.

81531831112 is a deficient number, since it is larger than the sum of its proper divisors (71340352238).

81531831112 is a wasteful number, since it uses less digits than its factorization.

81531831112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10191478895 (or 10191478891 counting only the distinct ones).

The product of its digits is 5760, while the sum is 34.

The spelling of 81531831112 in words is "eighty-one billion, five hundred thirty-one million, eight hundred thirty-one thousand, one hundred twelve".