666666739 has 4 divisors (see below), whose sum is σ = 666773824. Its totient is φ = 666559656.

The previous prime is 666666727. The next prime is 666666757. The reversal of 666666739 is 937666666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666666739 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666666739.

It is not an unprimeable number, because it can be changed into a prime (666666719) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43587 + ... + 56860.

It is an arithmetic number, because the mean of its divisors is an integer number (166693456).

Almost surely, 2^666666739 is an apocalyptic number.

666666739 is a deficient number, since it is larger than the sum of its proper divisors (107085).

666666739 is a wasteful number, since it uses less digits than its factorization.

666666739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107084.

The product of its digits is 8817984, while the sum is 55.

The square root of 666666739 is about 25819.8903754451. The cubic root of 666666739 is about 873.5804963308.

The spelling of 666666739 in words is "six hundred sixty-six million, six hundred sixty-six thousand, seven hundred thirty-nine".