18161781120 has 896 divisors, whose sum is σ = 76416963840. Its totient is φ = 4040036352.

The previous prime is 18161781119. The next prime is 18161781133. The reversal of 18161781120 is 2118716181.

18161781120 is a `hidden beast` number, since 1 + 8 + 1 + 617 + 8 + 11 + 20 = 666.

It is a tau number, because it is divible by the number of its divisors (896).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 218816599 + ... + 218816681.

It is an arithmetic number, because the mean of its divisors is an integer number (85286790).

Almost surely, 2^18161781120 is an apocalyptic number.

18161781120 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18161781120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38208481920).

18161781120 is an abundant number, since it is smaller than the sum of its proper divisors (58255182720).

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

18161781120 is an frugal number, since it uses more digits than its factorization.

18161781120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 36.

The spelling of 18161781120 in words is "eighteen billion, one hundred sixty-one million, seven hundred eighty-one thousand, one hundred twenty".