216665165 has 4 divisors (see below), whose sum is σ = 259998204. Its totient is φ = 173332128.

The previous prime is 216665161. The next prime is 216665171. The reversal of 216665165 is 561566612.

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 74149321 + 142515844 = 8611^2 + 11938^2 .

It is a cyclic number.

It is not a de Polignac number, because 216665165 - 2² = 216665161 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216665161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21666512 + ... + 21666521.

It is an arithmetic number, because the mean of its divisors is an integer number (64999551).

Almost surely, 2^216665165 is an apocalyptic number.

It is an amenable number.

216665165 is a deficient number, since it is larger than the sum of its proper divisors (43333039).

216665165 is an equidigital number, since it uses as much as digits as its factorization.

216665165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43333038.

The product of its digits is 64800, while the sum is 38.

The square root of 216665165 is about 14719.5504347110. The cubic root of 216665165 is about 600.6152623899.

The spelling of 216665165 in words is "two hundred sixteen million, six hundred sixty-five thousand, one hundred sixty-five".