81157525 has 6 divisors (see below), whose sum is σ = 100635362. Its totient is φ = 64926000.

The previous prime is 81157523. The next prime is 81157529. The reversal of 81157525 is 52575118.

It can be written as a sum of positive squares in 3 ways, for example, as 16499844 + 64657681 = 4062^2 + 8041^2 .

It is not a de Polignac number, because 81157525 - 2¹ = 81157523 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 (81157523) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1623126 + ... + 1623175.

Almost surely, 2^81157525 is an apocalyptic number.

It is an amenable number.

81157525 is a deficient number, since it is larger than the sum of its proper divisors (19477837).

81157525 is a wasteful number, since it uses less digits than its factorization.

81157525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3246311 (or 3246306 counting only the distinct ones).

The product of its digits is 14000, while the sum is 34.

The square root of 81157525 is about 9008.7471381985. The cubic root of 81157525 is about 432.9551713960.

The spelling of 81157525 in words is "eighty-one million, one hundred fifty-seven thousand, five hundred twenty-five".