81365538615 has 32 divisors (see below), whose sum is σ = 131879404800. Its totient is φ = 42831824640.

The previous prime is 81365538613. The next prime is 81365538619. The reversal of 81365538615 is 51683556318.

It is not a de Polignac number, because 81365538615 - 2¹ = 81365538613 is a prime.

It is a super-2 number, since 2×81365538615² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81365538613) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 708916 + ... + 815654.

It is an arithmetic number, because the mean of its divisors is an integer number (4121231400).

Almost surely, 2^81365538615 is an apocalyptic number.

81365538615 is a deficient number, since it is larger than the sum of its proper divisors (50513866185).

81365538615 is a wasteful number, since it uses less digits than its factorization.

81365538615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107407.

The product of its digits is 2592000, while the sum is 51.

The spelling of 81365538615 in words is "eighty-one billion, three hundred sixty-five million, five hundred thirty-eight thousand, six hundred fifteen".