18521580416 has 64 divisors (see below), whose sum is σ = 38482200960. Its totient is φ = 8869478400.

The previous prime is 18521580397. The next prime is 18521580421. The reversal of 18521580416 is 61408512581.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×18521580416² (a number of 21 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 (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 360836 + ... + 408956.

It is an arithmetic number, because the mean of its divisors is an integer number (601284390).

Almost surely, 2^18521580416 is an apocalyptic number.

18521580416 is a gapful number since it is divisible by the number (16) 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 18521580416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19241100480).

18521580416 is an abundant number, since it is smaller than the sum of its proper divisors (19960620544).

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

18521580416 is an equidigital number, since it uses as much as digits as its factorization.

18521580416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48263 (or 48251 counting only the distinct ones).

The product of its (nonzero) digits is 76800, while the sum is 41.

The spelling of 18521580416 in words is "eighteen billion, five hundred twenty-one million, five hundred eighty thousand, four hundred sixteen".