81607643125 has 20 divisors (see below), whose sum is σ = 102266073756. Its totient is φ = 65100992000.

The previous prime is 81607643119. The next prime is 81607643137. The reversal of 81607643125 is 52134670618.

It can be written as a sum of positive squares in 10 ways, for example, as 40865835409 + 40741807716 = 202153^2 + 201846^2 .

It is not a de Polignac number, because 81607643125 - 2⁵ = 81607643093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 35679 + ... + 405571.

Almost surely, 2^81607643125 is an apocalyptic number.

It is an amenable number.

81607643125 is a deficient number, since it is larger than the sum of its proper divisors (20658430631).

81607643125 is an equidigital number, since it uses as much as digits as its factorization.

81607643125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370266 (or 370251 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 43.

The spelling of 81607643125 in words is "eighty-one billion, six hundred seven million, six hundred forty-three thousand, one hundred twenty-five".