81388385125 has 8 divisors (see below), whose sum is σ = 101572704792. Its totient is φ = 65110708000.

The previous prime is 81388385119. The next prime is 81388385129. The reversal of 81388385125 is 52158388318.

It can be written as a sum of positive squares in 4 ways, for example, as 10769043076 + 70619342049 = 103774^2 + 265743^2 .

It is not a de Polignac number, because 81388385125 - 2⁹ = 81388384613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81388385129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 325553416 + ... + 325553665.

It is an arithmetic number, because the mean of its divisors is an integer number (12696588099).

Almost surely, 2^81388385125 is an apocalyptic number.

It is an amenable number.

81388385125 is a deficient number, since it is larger than the sum of its proper divisors (20184319667).

81388385125 is an equidigital number, since it uses as much as digits as its factorization.

81388385125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651107096 (or 651107086 counting only the distinct ones).

The product of its digits is 1843200, while the sum is 52.

The spelling of 81388385125 in words is "eighty-one billion, three hundred eighty-eight million, three hundred eighty-five thousand, one hundred twenty-five".