81541531592 has 32 divisors (see below), whose sum is σ = 155896990200. Its totient is φ = 39970205184.

The previous prime is 81541531573. The next prime is 81541531601. The reversal of 81541531592 is 29513514518.

It can be written as a sum of positive squares in 4 ways, for example, as 67046816356 + 14494715236 = 258934^2 + 120394^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 471938 + ... + 621134.

Almost surely, 2^81541531592 is an apocalyptic number.

It is an amenable number.

81541531592 is a deficient number, since it is larger than the sum of its proper divisors (74355458608).

81541531592 is a wasteful number, since it uses less digits than its factorization.

81541531592 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150545 (or 150541 counting only the distinct ones).

The product of its digits is 216000, while the sum is 44.

The spelling of 81541531592 in words is "eighty-one billion, five hundred forty-one million, five hundred thirty-one thousand, five hundred ninety-two".