2181837856665 has 32 divisors (see below), whose sum is σ = 3502287089280. Its totient is φ = 1159869735936.

The previous prime is 2181837856663. The next prime is 2181837856687. The reversal of 2181837856665 is 5666587381812.

It is not a de Polignac number, because 2181837856665 - 2¹ = 2181837856663 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2181837856596 and 2181837856605.

It is not an unprimeable number, because it can be changed into a prime (2181837856663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (31) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6786034 + ... + 7100276.

It is an arithmetic number, because the mean of its divisors is an integer number (109446471540).

Almost surely, 2^{2181837856665} is an apocalyptic number.

It is an amenable number.

2181837856665 is a deficient number, since it is larger than the sum of its proper divisors (1320449232615).

2181837856665 is a wasteful number, since it uses less digits than its factorization.

2181837856665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315753.

The product of its digits is 116121600, while the sum is 66.

The spelling of 2181837856665 in words is "two trillion, one hundred eighty-one billion, eight hundred thirty-seven million, eight hundred fifty-six thousand, six hundred sixty-five".