2181543849 has 9 divisors (see below), whose sum is σ = 3151321303. Its totient is φ = 1454269152.

The previous prime is 2181543827. The next prime is 2181543857. The reversal of 2181543849 is 9483451812.

The square root of 2181543849 is 46707.

It is a perfect power (a square), and thus also a powerful number.

2181543849 is a `hidden beast` number, since 21 + 8 + 1 + 543 + 84 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 815502249 + 1366041600 = 28557^2 + 36960^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 2181543849 - 2²¹ = 2179446697 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2181543149) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 132337 + ... + 147905.

Almost surely, 2^2181543849 is an apocalyptic number.

2181543849 is the 46707-th square number.

2181543849 is the 23354-th centered octagonal number.

It is an amenable number.

2181543849 is a deficient number, since it is larger than the sum of its proper divisors (969777454).

2181543849 is an frugal number, since it uses more digits than its factorization.

2181543849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31144 (or 15572 counting only the distinct ones).

The product of its digits is 276480, while the sum is 45.

The cubic root of 2181543849 is about 1296.9442724648.

The spelling of 2181543849 in words is "two billion, one hundred eighty-one million, five hundred forty-three thousand, eight hundred forty-nine".