2161864849 has 4 divisors (see below), whose sum is σ = 2162221236. Its totient is φ = 2161508464.

The previous prime is 2161864807. The next prime is 2161864853. The reversal of 2161864849 is 9484681612.

It is a happy number.

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 717864849 + 1444000000 = 26793^2 + 38000^2 .

It is a cyclic number.

It is not a de Polignac number, because 2161864849 - 2⁹ = 2161864337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2161864889) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 168934 + ... + 181279.

It is an arithmetic number, because the mean of its divisors is an integer number (540555309).

Almost surely, 2^2161864849 is an apocalyptic number.

It is an amenable number.

2161864849 is a deficient number, since it is larger than the sum of its proper divisors (356387).

2161864849 is an equidigital number, since it uses as much as digits as its factorization.

2161864849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356386.

The product of its digits is 663552, while the sum is 49.

The square root of 2161864849 is about 46495.8584069592. The cubic root of 2161864849 is about 1293.0327158430.

The spelling of 2161864849 in words is "two billion, one hundred sixty-one million, eight hundred sixty-four thousand, eight hundred forty-nine".