16561324800 has 648 divisors, whose sum is σ = 64211556864. Its totient is φ = 4215214080.

The previous prime is 16561324781. The next prime is 16561324847. The reversal of 16561324800 is 842316561.

It is a happy number.

16561324800 is a `hidden beast` number, since 16 + 5 + 613 + 24 + 8 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (648).

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 polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 35769369 + ... + 35769831.

Almost surely, 2^16561324800 is an apocalyptic number.

16561324800 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 16561324800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32105778432).

16561324800 is an abundant number, since it is smaller than the sum of its proper divisors (47650232064).

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

16561324800 is an equidigital number, since it uses as much as digits as its factorization.

16561324800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 527 (or 496 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 16561324800 in words is "sixteen billion, five hundred sixty-one million, three hundred twenty-four thousand, eight hundred".