6656666161 has 4 divisors (see below), whose sum is σ = 6657057792. Its totient is φ = 6656274532.

The previous prime is 6656666143. The next prime is 6656666173. The reversal of 6656666161 is 1616666566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6656666161 - 2⁵ = 6656666129 is a prime.

It is a super-2 number, since 2×6656666161² = 88622408758004955842, which contains 22 as substring.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6656676161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 169105 + ... + 204718.

It is an arithmetic number, because the mean of its divisors is an integer number (1664264448).

Almost surely, 2^6656666161 is an apocalyptic number.

It is an amenable number.

6656666161 is a deficient number, since it is larger than the sum of its proper divisors (391631).

6656666161 is a wasteful number, since it uses less digits than its factorization.

6656666161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391630.

The product of its digits is 1399680, while the sum is 49.

The square root of 6656666161 is about 81588.3947691092. The cubic root of 6656666161 is about 1881.1305031900.

The spelling of 6656666161 in words is "six billion, six hundred fifty-six million, six hundred sixty-six thousand, one hundred sixty-one".