81518719518 has 32 divisors (see below), whose sum is σ = 190687065600. Its totient is φ = 25742753208.

The previous prime is 81518719417. The next prime is 81518719531. The reversal of 81518719518 is 81591781518.

It is a happy number.

81518719518 is a `hidden beast` number, since 8 + 1 + 51 + 8 + 71 + 9 + 518 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39725446 + ... + 39727497.

It is an arithmetic number, because the mean of its divisors is an integer number (5958970800).

Almost surely, 2^81518719518 is an apocalyptic number.

81518719518 is an abundant number, since it is smaller than the sum of its proper divisors (109168346082).

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

81518719518 is a wasteful number, since it uses less digits than its factorization.

81518719518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79452973 (or 79452967 counting only the distinct ones).

The product of its digits is 806400, while the sum is 54.

The spelling of 81518719518 in words is "eighty-one billion, five hundred eighteen million, seven hundred nineteen thousand, five hundred eighteen".