216540085 has 4 divisors (see below), whose sum is σ = 259848108. Its totient is φ = 173232064.

The previous prime is 216540043. The next prime is 216540091. The reversal of 216540085 is 580045612.

216540085 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 25492401 + 191047684 = 5049^2 + 13822^2 .

It is a cyclic number.

It is not a de Polignac number, because 216540085 - 2⁷ = 216539957 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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, 21654004 + ... + 21654013.

It is an arithmetic number, because the mean of its divisors is an integer number (64962027).

Almost surely, 2^216540085 is an apocalyptic number.

It is an amenable number.

216540085 is a deficient number, since it is larger than the sum of its proper divisors (43308023).

216540085 is an equidigital number, since it uses as much as digits as its factorization.

216540085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43308022.

The product of its (nonzero) digits is 9600, while the sum is 31.

The square root of 216540085 is about 14715.3010502674. The cubic root of 216540085 is about 600.4996624839.

Adding to 216540085 its reverse (580045612), we get a palindrome (796585697).

The spelling of 216540085 in words is "two hundred sixteen million, five hundred forty thousand, eighty-five".