666561115 has 16 divisors (see below), whose sum is σ = 881235936. Its totient is φ = 479968000.

The previous prime is 666561107. The next prime is 666561187. The reversal of 666561115 is 511165666.

It is not a de Polignac number, because 666561115 - 2³ = 666561107 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 54442 + ... + 65551.

It is an arithmetic number, because the mean of its divisors is an integer number (55077246).

Almost surely, 2^666561115 is an apocalyptic number.

666561115 is a deficient number, since it is larger than the sum of its proper divisors (214674821).

666561115 is a wasteful number, since it uses less digits than its factorization.

666561115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120110.

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

The square root of 666561115 is about 25817.8448945686. The cubic root of 666561115 is about 873.5343583659.

The spelling of 666561115 in words is "six hundred sixty-six million, five hundred sixty-one thousand, one hundred fifteen".