16561979320500 has 192 divisors, whose sum is σ = 54248778205440. Its totient is φ = 4416527527200.

The previous prime is 16561979320477. The next prime is 16561979320507. The reversal of 16561979320500 is 502397916561.

16561979320500 is a `hidden beast` number, since 1 + 6 + 5 + 61 + 9 + 79 + 3 + 2 + 0 + 500 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16561979320507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6479422 + ... + 8666421.

It is an arithmetic number, because the mean of its divisors is an integer number (282545719820).

Almost surely, 2^{16561979320500} is an apocalyptic number.

16561979320500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16561979320500 is an abundant number, since it is smaller than the sum of its proper divisors (37686798884940).

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

16561979320500 is an equidigital number, since it uses as much as digits as its factorization.

16561979320500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15145883 (or 15145853 counting only the distinct ones).

The product of its (nonzero) digits is 3061800, while the sum is 54.

The spelling of 16561979320500 in words is "sixteen trillion, five hundred sixty-one billion, nine hundred seventy-nine million, three hundred twenty thousand, five hundred".