661655011206018 has 16 divisors (see below), whose sum is σ = 1325247518792736. Its totient is φ = 220228754338560.

The previous prime is 661655011205977. The next prime is 661655011206019. The reversal of 661655011206018 is 810602110556166.

It is not an unprimeable number, because it can be changed into a prime (661655011206019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80729011423 + ... + 80729019618.

It is an arithmetic number, because the mean of its divisors is an integer number (82827969924546).

Almost surely, 2^{661655011206018} is an apocalyptic number.

661655011206018 is an abundant number, since it is smaller than the sum of its proper divisors (663592507586718).

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

661655011206018 is a wasteful number, since it uses less digits than its factorization.

661655011206018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161458031729.

The product of its (nonzero) digits is 518400, while the sum is 48.

The spelling of 661655011206018 in words is "six hundred sixty-one trillion, six hundred fifty-five billion, eleven million, two hundred six thousand, eighteen".