16561920660 has 24 divisors (see below), whose sum is σ = 46373378016. Its totient is φ = 4416512160.

The previous prime is 16561920601. The next prime is 16561920671. The reversal of 16561920660 is 6602916561.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 138015946 + ... + 138016065.

It is an arithmetic number, because the mean of its divisors is an integer number (1932224084).

Almost surely, 2^16561920660 is an apocalyptic number.

16561920660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

16561920660 is an abundant number, since it is smaller than the sum of its proper divisors (29811457356).

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

16561920660 is a wasteful number, since it uses less digits than its factorization.

16561920660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276032023 (or 276032021 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 42.

The spelling of 16561920660 in words is "sixteen billion, five hundred sixty-one million, nine hundred twenty thousand, six hundred sixty".