661611655584 has 96 divisors (see below), whose sum is σ = 2105128025280. Its totient is φ = 200488377600.

The previous prime is 661611655561. The next prime is 661611655613. The reversal of 661611655584 is 485556116166.

It is a happy number.

661611655584 is a `hidden beast` number, since 6 + 6 + 1 + 6 + 1 + 1 + 6 + 55 + 584 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 661611655584.

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, 34797507 + ... + 34816514.

It is an arithmetic number, because the mean of its divisors is an integer number (21928416930).

Almost surely, 2^661611655584 is an apocalyptic number.

It is an amenable number.

661611655584 is an abundant number, since it is smaller than the sum of its proper divisors (1443516369696).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661611655584 is a wasteful number, since it uses less digits than its factorization.

661611655584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69614051 (or 69614037 counting only the distinct ones).

The product of its digits is 5184000, while the sum is 54.

The spelling of 661611655584 in words is "six hundred sixty-one billion, six hundred eleven million, six hundred fifty-five thousand, five hundred eighty-four".