661005516566 has 8 divisors (see below), whose sum is σ = 991512590160. Its totient is φ = 330501319848.

The previous prime is 661005516539. The next prime is 661005516607. The reversal of 661005516566 is 665615500166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 661005516566.

It is a congruent number.

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, 1601 + ... + 1149788.

It is an arithmetic number, because the mean of its divisors is an integer number (123939073770).

Almost surely, 2^661005516566 is an apocalyptic number.

661005516566 is a deficient number, since it is larger than the sum of its proper divisors (330507073594).

661005516566 is a wasteful number, since it uses less digits than its factorization.

661005516566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1438438.

The product of its (nonzero) digits is 972000, while the sum is 47.

The spelling of 661005516566 in words is "six hundred sixty-one billion, five million, five hundred sixteen thousand, five hundred sixty-six".