81563636518 has 32 divisors (see below), whose sum is σ = 157125943296. Its totient is φ = 30864021408.

The previous prime is 81563636471. The next prime is 81563636521.

81563636518 is nontrivially palindromic in base 10.

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 15 ways as a sum of consecutive naturals, for example, 9738246 + ... + 9746617.

It is an arithmetic number, because the mean of its divisors is an integer number (4910185728).

Almost surely, 2^81563636518 is an apocalyptic number.

81563636518 is a deficient number, since it is larger than the sum of its proper divisors (75562306778).

81563636518 is a wasteful number, since it uses less digits than its factorization.

81563636518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19484908.

The product of its digits is 3110400, while the sum is 52.

The spelling of 81563636518 in words is "eighty-one billion, five hundred sixty-three million, six hundred thirty-six thousand, five hundred eighteen".