216840005 has 4 divisors (see below), whose sum is σ = 260208012. Its totient is φ = 173472000.

The previous prime is 216839963. The next prime is 216840007. The reversal of 216840005 is 500048612.

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 171452836 + 45387169 = 13094^2 + 6737^2 .

It is not a de Polignac number, because 216840005 - 2¹⁸ = 216577861 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216840007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21683996 + ... + 21684005.

It is an arithmetic number, because the mean of its divisors is an integer number (65052003).

Almost surely, 2^216840005 is an apocalyptic number.

It is an amenable number.

216840005 is a deficient number, since it is larger than the sum of its proper divisors (43368007).

216840005 is an equidigital number, since it uses as much as digits as its factorization.

216840005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43368006.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 216840005 is about 14725.4882771336. The cubic root of 216840005 is about 600.7767763376.

Adding to 216840005 its reverse (500048612), we get a palindrome (716888617).

The spelling of 216840005 in words is "two hundred sixteen million, eight hundred forty thousand, five".