15661566660 has 48 divisors (see below), whose sum is σ = 44072784000. Its totient is φ = 4155427584.

The previous prime is 15661566649. The next prime is 15661566757. The reversal of 15661566660 is 6666516651.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 643905 + ... + 667784.

It is an arithmetic number, because the mean of its divisors is an integer number (918183000).

Almost surely, 2^15661566660 is an apocalyptic number.

15661566660 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

15661566660 is an abundant number, since it is smaller than the sum of its proper divisors (28411217340).

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

15661566660 is a wasteful number, since it uses less digits than its factorization.

15661566660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1311900 (or 1311898 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 15661566660 in words is "fifteen billion, six hundred sixty-one million, five hundred sixty-six thousand, six hundred sixty".