81732729257 has 4 divisors (see below), whose sum is σ = 82456027860. Its totient is φ = 81009430656.

The previous prime is 81732729223. The next prime is 81732729259. The reversal of 81732729257 is 75292723718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18415575616 + 63317153641 = 135704^2 + 251629^2 .

It is a cyclic number.

It is not a de Polignac number, because 81732729257 - 2¹² = 81732725161 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81732729199 and 81732729208.

It is not an unprimeable number, because it can be changed into a prime (81732729259) by changing a digit.

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, 361649132 + ... + 361649357.

It is an arithmetic number, because the mean of its divisors is an integer number (20614006965).

Almost surely, 2^81732729257 is an apocalyptic number.

It is an amenable number.

81732729257 is a deficient number, since it is larger than the sum of its proper divisors (723298603).

81732729257 is a wasteful number, since it uses less digits than its factorization.

81732729257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 723298602.

The product of its digits is 2963520, while the sum is 53.

The spelling of 81732729257 in words is "eighty-one billion, seven hundred thirty-two million, seven hundred twenty-nine thousand, two hundred fifty-seven".