81535081725 has 36 divisors (see below), whose sum is σ = 146070567552. Its totient is φ = 43475796000.

The previous prime is 81535081723. The next prime is 81535081751. The reversal of 81535081725 is 52718053518.

81535081725 is a `hidden beast` number, since 81 + 53 + 508 + 17 + 2 + 5 = 666.

It is not a de Polignac number, because 81535081725 - 2¹ = 81535081723 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81535081723) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1049470 + ... + 1124480.

Almost surely, 2^81535081725 is an apocalyptic number.

It is an amenable number.

81535081725 is a deficient number, since it is larger than the sum of its proper divisors (64535485827).

81535081725 is a wasteful number, since it uses less digits than its factorization.

81535081725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79858 (or 79850 counting only the distinct ones).

The product of its (nonzero) digits is 336000, while the sum is 45.

The spelling of 81535081725 in words is "eighty-one billion, five hundred thirty-five million, eighty-one thousand, seven hundred twenty-five".