661556605615 has 32 divisors (see below), whose sum is σ = 833705150976. Its totient is φ = 503330734080.

The previous prime is 661556605601. The next prime is 661556605673. The reversal of 661556605615 is 516506655166.

It is not a de Polignac number, because 661556605615 - 2¹⁷ = 661556474543 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3028719 + ... + 3239791.

It is an arithmetic number, because the mean of its divisors is an integer number (26053285968).

Almost surely, 2^661556605615 is an apocalyptic number.

661556605615 is a deficient number, since it is larger than the sum of its proper divisors (172148545361).

661556605615 is a wasteful number, since it uses less digits than its factorization.

661556605615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211459.

The product of its (nonzero) digits is 4860000, while the sum is 52.

The spelling of 661556605615 in words is "six hundred sixty-one billion, five hundred fifty-six million, six hundred five thousand, six hundred fifteen".