18043981956 has 576 divisors, whose sum is σ = 65049384960. Its totient is φ = 4197173760.

The previous prime is 18043981937. The next prime is 18043981957. The reversal of 18043981956 is 65918934081.

18043981956 is a `hidden beast` number, since 1 + 80 + 439 + 81 + 9 + 56 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (18043981957) 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 191 ways as a sum of consecutive naturals, for example, 51999775 + ... + 52000121.

It is an arithmetic number, because the mean of its divisors is an integer number (112932960).

Almost surely, 2^18043981956 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18043981956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32524692480).

18043981956 is an abundant number, since it is smaller than the sum of its proper divisors (47005403004).

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

18043981956 is a wasteful number, since it uses less digits than its factorization.

18043981956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 441 (or 420 counting only the distinct ones).

The product of its (nonzero) digits is 1866240, while the sum is 54.

It can be divided in two parts, 18043 and 981956, that added together give a palindrome (999999).

The spelling of 18043981956 in words is "eighteen billion, forty-three million, nine hundred eighty-one thousand, nine hundred fifty-six".