666560121 has 4 divisors (see below), whose sum is σ = 888746832. Its totient is φ = 444373412.

The previous prime is 666560119. The next prime is 666560137. The reversal of 666560121 is 121065666.

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 666560121 - 2¹ = 666560119 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666560101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111093351 + ... + 111093356.

It is an arithmetic number, because the mean of its divisors is an integer number (222186708).

Almost surely, 2^666560121 is an apocalyptic number.

It is an amenable number.

666560121 is a deficient number, since it is larger than the sum of its proper divisors (222186711).

666560121 is a wasteful number, since it uses less digits than its factorization.

666560121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222186710.

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 666560121 is about 25817.8256443102. The cubic root of 666560121 is about 873.5339241504.

The spelling of 666560121 in words is "six hundred sixty-six million, five hundred sixty thousand, one hundred twenty-one".