216509078809 has 4 divisors (see below), whose sum is σ = 217942913920. Its totient is φ = 215075243700.

The previous prime is 216509078803. The next prime is 216509078861. The reversal of 216509078809 is 908870905612.

216509078809 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216509078809 - 2²¹ = 216506981657 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 216509078809.

It is not an unprimeable number, because it can be changed into a prime (216509078803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 716917329 + ... + 716917630.

It is an arithmetic number, because the mean of its divisors is an integer number (54485728480).

Almost surely, 2^216509078809 is an apocalyptic number.

It is an amenable number.

216509078809 is a deficient number, since it is larger than the sum of its proper divisors (1433835111).

216509078809 is a wasteful number, since it uses less digits than its factorization.

216509078809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1433835110.

The product of its (nonzero) digits is 2177280, while the sum is 55.

It can be divided in two parts, 21650907 and 8809, that added together give a square (21659716 = 4654²).

The spelling of 216509078809 in words is "two hundred sixteen billion, five hundred nine million, seventy-eight thousand, eight hundred nine".