2181324865 has 4 divisors (see below), whose sum is σ = 2617589844. Its totient is φ = 1745059888.

The previous prime is 2181324839. The next prime is 2181324877. The reversal of 2181324865 is 5684231812.

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 1359470641 + 821854224 = 36871^2 + 28668^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181324865 - 2⁷ = 2181324737 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 218132482 + ... + 218132491.

It is an arithmetic number, because the mean of its divisors is an integer number (654397461).

Almost surely, 2^2181324865 is an apocalyptic number.

It is an amenable number.

2181324865 is a deficient number, since it is larger than the sum of its proper divisors (436264979).

2181324865 is an equidigital number, since it uses as much as digits as its factorization.

2181324865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 436264978.

The product of its digits is 92160, while the sum is 40.

The square root of 2181324865 is about 46704.6557101110. The cubic root of 2181324865 is about 1296.9008751328.

The spelling of 2181324865 in words is "two billion, one hundred eighty-one million, three hundred twenty-four thousand, eight hundred sixty-five".