81171525 has 24 divisors (see below), whose sum is σ = 137835424. Its totient is φ = 42120000.

The previous prime is 81171521. The next prime is 81171529. The reversal of 81171525 is 52517118.

It is an interprime number because it is at equal distance from previous prime (81171521) and next prime (81171529).

It is not a de Polignac number, because 81171525 - 2² = 81171521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81171492 and 81171501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81171521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11851 + ... + 17400.

Almost surely, 2^81171525 is an apocalyptic number.

It is an amenable number.

81171525 is a deficient number, since it is larger than the sum of its proper divisors (56663899).

81171525 is a wasteful number, since it uses less digits than its factorization.

81171525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29301 (or 29296 counting only the distinct ones).

The product of its digits is 2800, while the sum is 30.

The square root of 81171525 is about 9009.5241272778. The cubic root of 81171525 is about 432.9800654684.

The spelling of 81171525 in words is "eighty-one million, one hundred seventy-one thousand, five hundred twenty-five".