666666738 has 48 divisors (see below), whose sum is σ = 1459070496. Its totient is φ = 219985920.

The previous prime is 666666727. The next prime is 666666757. The reversal of 666666738 is 837666666.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 975745 + ... + 976427.

It is an arithmetic number, because the mean of its divisors is an integer number (30397302).

Almost surely, 2^666666738 is an apocalyptic number.

666666738 is an abundant number, since it is smaller than the sum of its proper divisors (792403758).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666666738 is a wasteful number, since it uses less digits than its factorization.

666666738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1159 (or 1156 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 54.

The square root of 666666738 is about 25819.8903560801. The cubic root of 666666738 is about 873.5804958940.

The spelling of 666666738 in words is "six hundred sixty-six million, six hundred sixty-six thousand, seven hundred thirty-eight".