666111161 has 4 divisors (see below), whose sum is σ = 666399012. Its totient is φ = 665823312.

The previous prime is 666111113. The next prime is 666111169. The reversal of 666111161 is 161111666.

666111161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161111666 = 2 ⋅80555833.

It can be written as a sum of positive squares in 2 ways, for example, as 508231936 + 157879225 = 22544^2 + 12565^2 .

It is a cyclic number.

It is not a de Polignac number, because 666111161 - 2⁶ = 666111097 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666111169) 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, 140426 + ... + 145091.

It is an arithmetic number, because the mean of its divisors is an integer number (166599753).

Almost surely, 2^666111161 is an apocalyptic number.

It is an amenable number.

666111161 is a deficient number, since it is larger than the sum of its proper divisors (287851).

666111161 is a wasteful number, since it uses less digits than its factorization.

666111161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287850.

The product of its digits is 1296, while the sum is 29.

The square root of 666111161 is about 25809.1294118961. The cubic root of 666111161 is about 873.3377578621.

The spelling of 666111161 in words is "six hundred sixty-six million, one hundred eleven thousand, one hundred sixty-one".