216009 has 6 divisors (see below), whose sum is σ = 312026. Its totient is φ = 144000.

The previous prime is 215983. The next prime is 216023. The reversal of 216009 is 900612.

It can be written as a sum of positive squares in only one way, i.e., 164025 + 51984 = 405^2 + 228^2 .

It is not a de Polignac number, because 216009 - 2⁸ = 215753 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a junction number, because it is equal to n+sod(n) for n = 215982 and 216000.

It is not an unprimeable number, because it can be changed into a prime (216509) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11992 + ... + 12009.

216009 is a Friedman number, since it can be written as 60^(2+1+0)+9, using all its digits and the basic arithmetic operations.

2²¹⁶⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

216009 is a deficient number, since it is larger than the sum of its proper divisors (96017).

216009 is a wasteful number, since it uses less digits than its factorization.

216009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24007 (or 24004 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 216009 is about 464.7676839024. The cubic root of 216009 is about 60.0008333218. Note that the first 3 decimals are identical.

It can be divided in two parts, 21600 and 9, that added together give a square (21609 = 147²).

The spelling of 216009 in words is "two hundred sixteen thousand, nine".