2181543857 has 2 divisors, whose sum is σ = 2181543858. Its totient is φ = 2181543856.

The previous prime is 2181543827. The next prime is 2181543893. The reversal of 2181543857 is 7583451812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1801917601 + 379626256 = 42449^2 + 19484^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181543857 - 2²⁰ = 2180495281 is a prime.

It is not a weakly prime, because it can be changed into another prime (2181543827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090771928 + 1090771929.

It is an arithmetic number, because the mean of its divisors is an integer number (1090771929).

Almost surely, 2^2181543857 is an apocalyptic number.

It is an amenable number.

2181543857 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181543857 is an equidigital number, since it uses as much as digits as its factorization.

2181543857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 268800, while the sum is 44.

The square root of 2181543857 is about 46707.0000856403. Note that the first 4 decimals coincide. The cubic root of 2181543857 is about 1296.9442740502.

The spelling of 2181543857 in words is "two billion, one hundred eighty-one million, five hundred forty-three thousand, eight hundred fifty-seven".