661893980566 has 32 divisors (see below), whose sum is σ = 1227437826048. Its totient is φ = 260673945120.

The previous prime is 661893980551. The next prime is 661893980591. The reversal of 661893980566 is 665089398166.

It is a happy number.

661893980566 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8113630 + ... + 8194801.

It is an arithmetic number, because the mean of its divisors is an integer number (38357432064).

Almost surely, 2^661893980566 is an apocalyptic number.

661893980566 is a deficient number, since it is larger than the sum of its proper divisors (565543845482).

661893980566 is a wasteful number, since it uses less digits than its factorization.

661893980566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16308676.

The product of its (nonzero) digits is 100776960, while the sum is 67.

The spelling of 661893980566 in words is "six hundred sixty-one billion, eight hundred ninety-three million, nine hundred eighty thousand, five hundred sixty-six".