216585 has 12 divisors (see below), whose sum is σ = 375492. Its totient is φ = 115488.

The previous prime is 216577. The next prime is 216607. The reversal of 216585 is 585612.

216585 is a `hidden beast` number, since 2 + 1 + 658 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 121104 + 95481 = 348^2 + 309^2 .

It is not a de Polignac number, because 216585 - 2³ = 216577 is a prime.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is an alternating number because its digits alternate between even and odd.

216585 is a lucky number.

It is a nialpdrome in base 13.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2362 + ... + 2451.

It is an arithmetic number, because the mean of its divisors is an integer number (31291).

2²¹⁶⁵⁸⁵ is an apocalyptic number.

It is an amenable number.

216585 is a deficient number, since it is larger than the sum of its proper divisors (158907).

216585 is a wasteful number, since it uses less digits than its factorization.

216585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4824 (or 4821 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 216585 is about 465.3869357857. The cubic root of 216585 is about 60.0541178396.

Adding to 216585 its sum of digits (27), we get a palindrome (216612).

Subtracting from 216585 its product of digits (2400), we obtain a triangular number (214185 = T₆₅₄).

The spelling of 216585 in words is "two hundred sixteen thousand, five hundred eighty-five".