661565616016 has 20 divisors (see below), whose sum is σ = 1298008489600. Its totient is φ = 326595683232.

The previous prime is 661565616011. The next prime is 661565616017. The reversal of 661565616016 is 610616565166.

It is not an unprimeable number, because it can be changed into a prime (661565616011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 261693996 + ... + 261696523.

It is an arithmetic number, because the mean of its divisors is an integer number (64900424480).

Almost surely, 2^661565616016 is an apocalyptic number.

It is an amenable number.

661565616016 is a deficient number, since it is larger than the sum of its proper divisors (636442873584).

661565616016 is a wasteful number, since it uses less digits than its factorization.

661565616016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 523390606 (or 523390600 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 661565616016 in words is "six hundred sixty-one billion, five hundred sixty-five million, six hundred sixteen thousand, sixteen".