2181981618036 has 72 divisors (see below), whose sum is σ = 6017706021600. Its totient is φ = 661126726080.

The previous prime is 2181981618013. The next prime is 2181981618043. The reversal of 2181981618036 is 6308161891812.

It is a happy number.

2181981618036 is a `hidden beast` number, since 2 + 1 + 8 + 19 + 8 + 1 + 618 + 0 + 3 + 6 = 666.

It is a super-2 number, since 2×2181981618036² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2993635 + ... + 3650453.

It is an arithmetic number, because the mean of its divisors is an integer number (83579250300).

Almost surely, 2^{2181981618036} is an apocalyptic number.

It is an amenable number.

2181981618036 is an abundant number, since it is smaller than the sum of its proper divisors (3835724403564).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2181981618036 is a wasteful number, since it uses less digits than its factorization.

2181981618036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 665229 (or 665224 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 54.

The spelling of 2181981618036 in words is "two trillion, one hundred eighty-one billion, nine hundred eighty-one million, six hundred eighteen thousand, thirty-six".