66656161 has 16 divisors (see below), whose sum is σ = 82434240. Its totient is φ = 52989120.

The previous prime is 66656153. The next prime is 66656179. The reversal of 66656161 is 16165666.

It is a cyclic number.

It is not a de Polignac number, because 66656161 - 2³ = 66656153 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66656161.

It is not an unprimeable number, because it can be changed into a prime (66656111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9550 + ... + 14983.

It is an arithmetic number, because the mean of its divisors is an integer number (5152140).

Almost surely, 2^66656161 is an apocalyptic number.

It is an amenable number.

66656161 is a deficient number, since it is larger than the sum of its proper divisors (15778079).

66656161 is a wasteful number, since it uses less digits than its factorization.

66656161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24576.

The product of its digits is 38880, while the sum is 37.

The square root of 66656161 is about 8164.3224458616. The cubic root of 66656161 is about 405.4588327237.

The spelling of 66656161 in words is "sixty-six million, six hundred fifty-six thousand, one hundred sixty-one".