81610529765 has 4 divisors (see below), whose sum is σ = 97932635724. Its totient is φ = 65288423808.

The previous prime is 81610529603. The next prime is 81610529789. The reversal of 81610529765 is 56792501618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56792501618 = 2 ⋅28396250809.

It can be written as a sum of positive squares in 2 ways, for example, as 55923736324 + 25686793441 = 236482^2 + 160271^2 .

It is a cyclic number.

It is not a de Polignac number, because 81610529765 - 2²⁶ = 81543420901 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 8161052972 + ... + 8161052981.

It is an arithmetic number, because the mean of its divisors is an integer number (24483158931).

Almost surely, 2^81610529765 is an apocalyptic number.

It is an amenable number.

81610529765 is a deficient number, since it is larger than the sum of its proper divisors (16322105959).

81610529765 is a wasteful number, since it uses less digits than its factorization.

81610529765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16322105958.

The product of its (nonzero) digits is 907200, while the sum is 50.

The spelling of 81610529765 in words is "eighty-one billion, six hundred ten million, five hundred twenty-nine thousand, seven hundred sixty-five".