181561504320 has 896 divisors, whose sum is σ = 761248972800. Its totient is φ = 39862886400.

The previous prime is 181561504297. The next prime is 181561504337. The reversal of 181561504320 is 23405165181.

181561504320 is a `hidden beast` number, since 1 + 8 + 1 + 5 + 615 + 0 + 4 + 32 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 335603250 + ... + 335603790.

Almost surely, 2^181561504320 is an apocalyptic number.

181561504320 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 181561504320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (380624486400).

181561504320 is an abundant number, since it is smaller than the sum of its proper divisors (579687468480).

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

181561504320 is a wasteful number, since it uses less digits than its factorization.

181561504320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 784 (or 768 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The spelling of 181561504320 in words is "one hundred eighty-one billion, five hundred sixty-one million, five hundred four thousand, three hundred twenty".