81753865 has 12 divisors (see below), whose sum is σ = 103542084. Its totient is φ = 61959456.

The previous prime is 81753863. The next prime is 81753911. The reversal of 81753865 is 56835718.

It can be written as a sum of positive squares in 2 ways, for example, as 40998409 + 40755456 = 6403^2 + 6384^2 .

It is not a de Polignac number, because 81753865 - 2¹ = 81753863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81753863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20842 + ... + 24451.

It is an arithmetic number, because the mean of its divisors is an integer number (8628507).

Almost surely, 2^81753865 is an apocalyptic number.

It is an amenable number.

81753865 is a deficient number, since it is larger than the sum of its proper divisors (21788219).

81753865 is a wasteful number, since it uses less digits than its factorization.

81753865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45336 (or 45317 counting only the distinct ones).

The product of its digits is 201600, while the sum is 43.

The square root of 81753865 is about 9041.7843924748. The cubic root of 81753865 is about 434.0130263598.

The spelling of 81753865 in words is "eighty-one million, seven hundred fifty-three thousand, eight hundred sixty-five".