666812215 has 16 divisors (see below), whose sum is σ = 811556928. Its totient is φ = 525908736.

The previous prime is 666812189. The next prime is 666812227. The reversal of 666812215 is 512218666.

It is a cyclic number.

It is not a de Polignac number, because 666812215 - 2⁵ = 666812183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 117217 + ... + 122773.

It is an arithmetic number, because the mean of its divisors is an integer number (50722308).

Almost surely, 2^666812215 is an apocalyptic number.

666812215 is a deficient number, since it is larger than the sum of its proper divisors (144744713).

666812215 is a wasteful number, since it uses less digits than its factorization.

666812215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5898.

The product of its digits is 34560, while the sum is 37.

The square root of 666812215 is about 25822.7073522510. The cubic root of 666812215 is about 873.6440342006.

The spelling of 666812215 in words is "six hundred sixty-six million, eight hundred twelve thousand, two hundred fifteen".