81125565 has 16 divisors (see below), whose sum is σ = 130032000. Its totient is φ = 43189952.

The previous prime is 81125537. The next prime is 81125567. The reversal of 81125565 is 56552118.

It is a cyclic number.

It is not a de Polignac number, because 81125565 - 2⁵ = 81125533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81125567) 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, 4471 + ... + 13499.

It is an arithmetic number, because the mean of its divisors is an integer number (8127000).

Almost surely, 2^81125565 is an apocalyptic number.

It is an amenable number.

81125565 is a deficient number, since it is larger than the sum of its proper divisors (48906435).

81125565 is a wasteful number, since it uses less digits than its factorization.

81125565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9636.

The product of its digits is 12000, while the sum is 33.

The square root of 81125565 is about 9006.9731319684. The cubic root of 81125565 is about 432.8983310556.

The spelling of 81125565 in words is "eighty-one million, one hundred twenty-five thousand, five hundred sixty-five".