2180021809 has 24 divisors (see below), whose sum is σ = 2717553888. Its totient is φ = 1737429120.

The previous prime is 2180021801. The next prime is 2180021887. The reversal of 2180021809 is 9081200812.

It is a happy number.

It is not a de Polignac number, because 2180021809 - 2³ = 2180021801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2180021801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53374 + ... + 84904.

It is an arithmetic number, because the mean of its divisors is an integer number (113231412).

Almost surely, 2^2180021809 is an apocalyptic number.

It is an amenable number.

2180021809 is a deficient number, since it is larger than the sum of its proper divisors (537532079).

2180021809 is a wasteful number, since it uses less digits than its factorization.

2180021809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31645 (or 31638 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 2180021809 is about 46690.7036678609. The cubic root of 2180021809 is about 1296.6425808716.

The spelling of 2180021809 in words is "two billion, one hundred eighty million, twenty-one thousand, eight hundred nine".