81315472518 has 48 divisors (see below), whose sum is σ = 201586185216. Its totient is φ = 23206039920.

The previous prime is 81315472489. The next prime is 81315472549. The reversal of 81315472518 is 81527451318.

81315472518 is a `hidden beast` number, since 8 + 13 + 1 + 54 + 72 + 518 = 666.

It is a super-2 number, since 2×81315472518² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 265168 + ... + 482643.

It is an arithmetic number, because the mean of its divisors is an integer number (4199712192).

Almost surely, 2^81315472518 is an apocalyptic number.

81315472518 is an abundant number, since it is smaller than the sum of its proper divisors (120270712698).

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

81315472518 is a wasteful number, since it uses less digits than its factorization.

81315472518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 748689 (or 748686 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The spelling of 81315472518 in words is "eighty-one billion, three hundred fifteen million, four hundred seventy-two thousand, five hundred eighteen".