81545565 has 16 divisors (see below), whose sum is σ = 130837248. Its totient is φ = 43369536.

The previous prime is 81545561. The next prime is 81545609. The reversal of 81545565 is 56554518.

It is not a de Polignac number, because 81545565 - 2² = 81545561 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81545561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1902 + ... + 12911.

It is an arithmetic number, because the mean of its divisors is an integer number (8177328).

Almost surely, 2^81545565 is an apocalyptic number.

It is an amenable number.

81545565 is a deficient number, since it is larger than the sum of its proper divisors (49291683).

81545565 is a wasteful number, since it uses less digits than its factorization.

81545565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15188.

The product of its digits is 120000, while the sum is 39.

The square root of 81545565 is about 9030.2583019535. The cubic root of 81545565 is about 433.6441067868.

The spelling of 81545565 in words is "eighty-one million, five hundred forty-five thousand, five hundred sixty-five".