2181209823 has 96 divisors (see below), whose sum is σ = 3730272000. Its totient is φ = 1255512960.

The previous prime is 2181209759. The next prime is 2181209843. The reversal of 2181209823 is 3289021812.

It is not a de Polignac number, because 2181209823 - 2⁶ = 2181209759 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181209843) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 12050793 + ... + 12050973.

It is an arithmetic number, because the mean of its divisors is an integer number (38857000).

Almost surely, 2^2181209823 is an apocalyptic number.

2181209823 is a deficient number, since it is larger than the sum of its proper divisors (1549062177).

2181209823 is a wasteful number, since it uses less digits than its factorization.

2181209823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 374 (or 355 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 2181209823 is about 46703.4241035922. The cubic root of 2181209823 is about 1296.8780754274.

The spelling of 2181209823 in words is "two billion, one hundred eighty-one million, two hundred nine thousand, eight hundred twenty-three".