81591442384 has 20 divisors (see below), whose sum is σ = 158099791680. Its totient is φ = 40791496160.

The previous prime is 81591442367. The next prime is 81591442393. The reversal of 81591442384 is 48324419518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101722 + ... + 416569.

It is an arithmetic number, because the mean of its divisors is an integer number (7904989584).

Almost surely, 2^81591442384 is an apocalyptic number.

It is an amenable number.

81591442384 is a deficient number, since it is larger than the sum of its proper divisors (76508349296).

81591442384 is a wasteful number, since it uses less digits than its factorization.

81591442384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528138 (or 528132 counting only the distinct ones).

The product of its digits is 1105920, while the sum is 49.

The spelling of 81591442384 in words is "eighty-one billion, five hundred ninety-one million, four hundred forty-two thousand, three hundred eighty-four".