18561729312 has 240 divisors, whose sum is σ = 63323346240. Its totient is φ = 5223854592.

The previous prime is 18561729311. The next prime is 18561729331. The reversal of 18561729312 is 21392716581.

18561729312 is a `hidden beast` number, since 1 + 8 + 5 + 617 + 29 + 3 + 1 + 2 = 666.

It is not an unprimeable number, because it can be changed into a prime (18561729311) by changing a digit.

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 39 ways as a sum of consecutive naturals, for example, 1208014 + ... + 1223282.

It is an arithmetic number, because the mean of its divisors is an integer number (263847276).

Almost surely, 2^18561729312 is an apocalyptic number.

18561729312 is a gapful number since it is divisible by the number (12) 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 18561729312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31661673120).

18561729312 is an abundant number, since it is smaller than the sum of its proper divisors (44761616928).

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

18561729312 is a wasteful number, since it uses less digits than its factorization.

18561729312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15365 (or 15348 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The spelling of 18561729312 in words is "eighteen billion, five hundred sixty-one million, seven hundred twenty-nine thousand, three hundred twelve".