81497565 has 24 divisors (see below), whose sum is σ = 143203320. Its totient is φ = 42868224.

The previous prime is 81497561. The next prime is 81497573. The reversal of 81497565 is 56579418.

81497565 is a `hidden beast` number, since 81 + 4 + 9 + 7 + 565 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 23707161 + 57790404 = 4869^2 + 7602^2 .

It is not a de Polignac number, because 81497565 - 2² = 81497561 is a prime.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81497565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81497561) 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 23 ways as a sum of consecutive naturals, for example, 9120 + ... + 15689.

It is an arithmetic number, because the mean of its divisors is an integer number (5966805).

Almost surely, 2^81497565 is an apocalyptic number.

It is an amenable number.

81497565 is a deficient number, since it is larger than the sum of its proper divisors (61705755).

81497565 is a wasteful number, since it uses less digits than its factorization.

81497565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24893 (or 24890 counting only the distinct ones).

The product of its digits is 302400, while the sum is 45.

The square root of 81497565 is about 9027.6001794497. The cubic root of 81497565 is about 433.5590050708.

The spelling of 81497565 in words is "eighty-one million, four hundred ninety-seven thousand, five hundred sixty-five".