661506006609 has 64 divisors (see below), whose sum is σ = 1216989184000. Its totient is φ = 346556568960.

The previous prime is 661506006587. The next prime is 661506006643. The reversal of 661506006609 is 906600605166.

It is not a de Polignac number, because 661506006609 - 2²⁰ = 661504958033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661506006209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2859844 + ... + 3082485.

It is an arithmetic number, because the mean of its divisors is an integer number (19015456000).

Almost surely, 2^661506006609 is an apocalyptic number.

It is an amenable number.

661506006609 is a deficient number, since it is larger than the sum of its proper divisors (555483177391).

661506006609 is a wasteful number, since it uses less digits than its factorization.

661506006609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5942395 (or 5942389 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The spelling of 661506006609 in words is "six hundred sixty-one billion, five hundred six million, six thousand, six hundred nine".