666515161 has 4 divisors (see below), whose sum is σ = 717785572. Its totient is φ = 615244752.

The previous prime is 666515119. The next prime is 666515173. The reversal of 666515161 is 161515666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53655625 + 612859536 = 7325^2 + 24756^2 .

It is a cyclic number.

It is not a de Polignac number, because 666515161 - 2⁹ = 666514649 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 666515161.

It is not an unprimeable number, because it can be changed into a prime (666525161) 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, 25635186 + ... + 25635211.

It is an arithmetic number, because the mean of its divisors is an integer number (179446393).

Almost surely, 2^666515161 is an apocalyptic number.

It is an amenable number.

666515161 is a deficient number, since it is larger than the sum of its proper divisors (51270411).

666515161 is a wasteful number, since it uses less digits than its factorization.

666515161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51270410.

The product of its digits is 32400, while the sum is 37.

The square root of 666515161 is about 25816.9549133898. The cubic root of 666515161 is about 873.5142835273.

The spelling of 666515161 in words is "six hundred sixty-six million, five hundred fifteen thousand, one hundred sixty-one".