2181686817 has 4 divisors (see below), whose sum is σ = 2908915760. Its totient is φ = 1454457876.

The previous prime is 2181686809. The next prime is 2181686851. The reversal of 2181686817 is 7186861812.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2181686817 - 2³ = 2181686809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2181686867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 363614467 + ... + 363614472.

It is an arithmetic number, because the mean of its divisors is an integer number (727228940).

Almost surely, 2^2181686817 is an apocalyptic number.

It is an amenable number.

2181686817 is a deficient number, since it is larger than the sum of its proper divisors (727228943).

2181686817 is an equidigital number, since it uses as much as digits as its factorization.

2181686817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 727228942.

The product of its digits is 258048, while the sum is 48.

The square root of 2181686817 is about 46708.5304521562. The cubic root of 2181686817 is about 1296.9726036974.

The spelling of 2181686817 in words is "two billion, one hundred eighty-one million, six hundred eighty-six thousand, eight hundred seventeen".