666666909 has 8 divisors (see below), whose sum is σ = 987654720. Its totient is φ = 444444588.

The previous prime is 666666907. The next prime is 666666943. The reversal of 666666909 is 909666666.

It is not a de Polignac number, because 666666909 - 2¹ = 666666907 is a prime.

It is a super-2 number, since 2×666666909² = 888889535111228562, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666666907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12345657 + ... + 12345710.

It is an arithmetic number, because the mean of its divisors is an integer number (123456840).

Almost surely, 2^666666909 is an apocalyptic number.

It is an amenable number.

666666909 is a deficient number, since it is larger than the sum of its proper divisors (320987811).

666666909 is a wasteful number, since it uses less digits than its factorization.

666666909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24691376 (or 24691370 counting only the distinct ones).

The product of its (nonzero) digits is 3779136, while the sum is 54.

The square root of 666666909 is about 25819.8936674805. The cubic root of 666666909 is about 873.5805705851.

The spelling of 666666909 in words is "six hundred sixty-six million, six hundred sixty-six thousand, nine hundred nine".