666666839 has 8 divisors (see below), whose sum is σ = 673505280. Its totient is φ = 659862616.

The previous prime is 666666829. The next prime is 666666841. The reversal of 666666839 is 938666666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666666839 - 2²⁰ = 665618263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666666809) 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, 31562 + ... + 48264.

It is an arithmetic number, because the mean of its divisors is an integer number (84188160).

Almost surely, 2^666666839 is an apocalyptic number.

666666839 is a deficient number, since it is larger than the sum of its proper divisors (6838441).

666666839 is a wasteful number, since it uses less digits than its factorization.

666666839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17109.

The product of its digits is 10077696, while the sum is 56.

The square root of 666666839 is about 25819.8923119365. The cubic root of 666666839 is about 873.5805400098.

The spelling of 666666839 in words is "six hundred sixty-six million, six hundred sixty-six thousand, eight hundred thirty-nine".