66611561656 has 16 divisors (see below), whose sum is σ = 125144989200. Its totient is φ = 33239564544.

The previous prime is 66611561641. The next prime is 66611561663. The reversal of 66611561656 is 65616511666.

66611561656 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, 8272761 + ... + 8280808.

It is an arithmetic number, because the mean of its divisors is an integer number (7821561825).

Almost surely, 2^66611561656 is an apocalyptic number.

It is an amenable number.

66611561656 is a deficient number, since it is larger than the sum of its proper divisors (58533427544).

66611561656 is a wasteful number, since it uses less digits than its factorization.

66611561656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16554078 (or 16554074 counting only the distinct ones).

The product of its digits is 1166400, while the sum is 49.

The spelling of 66611561656 in words is "sixty-six billion, six hundred eleven million, five hundred sixty-one thousand, six hundred fifty-six".