661515655056 has 80 divisors (see below), whose sum is σ = 1847476248000. Its totient is φ = 203253732864.

The previous prime is 661515655027. The next prime is 661515655061. The reversal of 661515655056 is 650556515166.

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 15 ways as a sum of consecutive naturals, for example, 9768231 + ... + 9835718.

It is an arithmetic number, because the mean of its divisors is an integer number (23093453100).

Almost surely, 2^661515655056 is an apocalyptic number.

It is an amenable number.

661515655056 is an abundant number, since it is smaller than the sum of its proper divisors (1185960592944).

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

661515655056 is a wasteful number, since it uses less digits than its factorization.

661515655056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19604016 (or 19604010 counting only the distinct ones).

The product of its (nonzero) digits is 4050000, while the sum is 51.

The spelling of 661515655056 in words is "six hundred sixty-one billion, five hundred fifteen million, six hundred fifty-five thousand, fifty-six".