81775508508 has 72 divisors (see below), whose sum is σ = 217741596800. Its totient is φ = 25805830176.

The previous prime is 81775508497. The next prime is 81775508543. The reversal of 81775508508 is 80580557718.

81775508508 is a `hidden beast` number, since 8 + 1 + 7 + 7 + 550 + 85 + 0 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 956985 + ... + 1038927.

Almost surely, 2^81775508508 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81775508508, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108870798400).

81775508508 is an abundant number, since it is smaller than the sum of its proper divisors (135966088292).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81775508508 is a wasteful number, since it uses less digits than its factorization.

81775508508 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83431 (or 83426 counting only the distinct ones).

The product of its (nonzero) digits is 3136000, while the sum is 54.

The spelling of 81775508508 in words is "eighty-one billion, seven hundred seventy-five million, five hundred eight thousand, five hundred eight".