8181665 has 4 divisors (see below), whose sum is σ = 9818004. Its totient is φ = 6545328.

The previous prime is 8181637. The next prime is 8181697. The reversal of 8181665 is 5661818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1175056 + 7006609 = 1084^2 + 2647^2 .

It is a cyclic number.

It is not a de Polignac number, because 8181665 - 2⁶ = 8181601 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 818162 + ... + 818171.

It is an arithmetic number, because the mean of its divisors is an integer number (2454501).

Almost surely, 2^8181665 is an apocalyptic number.

It is an amenable number.

8181665 is a deficient number, since it is larger than the sum of its proper divisors (1636339).

8181665 is a wasteful number, since it uses less digits than its factorization.

8181665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1636338.

The product of its digits is 11520, while the sum is 35.

The square root of 8181665 is about 2860.3609912037. The cubic root of 8181665 is about 201.5025583233.

The spelling of 8181665 in words is "eight million, one hundred eighty-one thousand, six hundred sixty-five".