81131612 has 6 divisors (see below), whose sum is σ = 141980328. Its totient is φ = 40565804.

The previous prime is 81131597. The next prime is 81131623. The reversal of 81131612 is 21613118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10141448 + ... + 10141455.

It is an arithmetic number, because the mean of its divisors is an integer number (23663388).

Almost surely, 2^81131612 is an apocalyptic number.

It is an amenable number.

81131612 is a deficient number, since it is larger than the sum of its proper divisors (60848716).

81131612 is a wasteful number, since it uses less digits than its factorization.

81131612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20282907 (or 20282905 counting only the distinct ones).

The product of its digits is 288, while the sum is 23.

The square root of 81131612 is about 9007.3088100720. The cubic root of 81131612 is about 432.9090866917.

It can be divided in two parts, 811 and 31612, that added together give a palindrome (32423).

The spelling of 81131612 in words is "eighty-one million, one hundred thirty-one thousand, six hundred twelve".