666640161 has 24 divisors (see below), whose sum is σ = 1064864736. Its totient is φ = 398485440.

The previous prime is 666640153. The next prime is 666640231. The reversal of 666640161 is 161046666.

It is not a de Polignac number, because 666640161 - 2³ = 666640153 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (666640561) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38895 + ... + 53348.

It is an arithmetic number, because the mean of its divisors is an integer number (44369364).

Almost surely, 2^666640161 is an apocalyptic number.

It is an amenable number.

666640161 is a deficient number, since it is larger than the sum of its proper divisors (398224575).

666640161 is a wasteful number, since it uses less digits than its factorization.

666640161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92333 (or 92330 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 666640161 is about 25819.3756895863. The cubic root of 666640161 is about 873.5688871666.

The spelling of 666640161 in words is "six hundred sixty-six million, six hundred forty thousand, one hundred sixty-one".