81689518725 has 24 divisors (see below), whose sum is σ = 135143627040. Its totient is φ = 43540768320.

The previous prime is 81689518723. The next prime is 81689518789. The reversal of 81689518725 is 52781598618.

It is not a de Polignac number, because 81689518725 - 2¹ = 81689518723 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81689518721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 214954 + ... + 457803.

It is an arithmetic number, because the mean of its divisors is an integer number (5630984460).

Almost surely, 2^81689518725 is an apocalyptic number.

It is an amenable number.

81689518725 is a deficient number, since it is larger than the sum of its proper divisors (53454108315).

81689518725 is a wasteful number, since it uses less digits than its factorization.

81689518725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 674389 (or 674384 counting only the distinct ones).

The product of its digits is 9676800, while the sum is 60.

The spelling of 81689518725 in words is "eighty-one billion, six hundred eighty-nine million, five hundred eighteen thousand, seven hundred twenty-five".