81191510584 has 32 divisors (see below), whose sum is σ = 153000540000. Its totient is φ = 40391747712.

The previous prime is 81191510557. The next prime is 81191510599. The reversal of 81191510584 is 48501519118.

It is a super-2 number, since 2×81191510584² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81191510584.

It is a congruent number.

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, 1720942 + ... + 1767490.

It is an arithmetic number, because the mean of its divisors is an integer number (4781266875).

Almost surely, 2^81191510584 is an apocalyptic number.

It is an amenable number.

81191510584 is a deficient number, since it is larger than the sum of its proper divisors (71809029416).

81191510584 is a wasteful number, since it uses less digits than its factorization.

81191510584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47647 (or 47643 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 43.

The spelling of 81191510584 in words is "eighty-one billion, one hundred ninety-one million, five hundred ten thousand, five hundred eighty-four".