661565556616 has 16 divisors (see below), whose sum is σ = 1240849080000. Its totient is φ = 330672468624.

The previous prime is 661565556581. The next prime is 661565556689. The reversal of 661565556616 is 616655565166.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13763220 + ... + 13811203.

It is an arithmetic number, because the mean of its divisors is an integer number (77553067500).

Almost surely, 2^661565556616 is an apocalyptic number.

It is an amenable number.

661565556616 is a deficient number, since it is larger than the sum of its proper divisors (579283523384).

661565556616 is a wasteful number, since it uses less digits than its factorization.

661565556616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27577428 (or 27577424 counting only the distinct ones).

The product of its digits is 29160000, while the sum is 58.

The spelling of 661565556616 in words is "six hundred sixty-one billion, five hundred sixty-five million, five hundred fifty-six thousand, six hundred sixteen".