666994 has 4 divisors (see below), whose sum is σ = 1000494. Its totient is φ = 333496.

The previous prime is 666989. The next prime is 667013. The reversal of 666994 is 499666.

666994 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 499666 = 2 ⋅249833.

It can be written as a sum of positive squares in only one way, i.e., 632025 + 34969 = 795^2 + 187^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166747 + ... + 166750.

2⁶⁶⁶⁹⁹⁴ is an apocalyptic number.

666994 is a deficient number, since it is larger than the sum of its proper divisors (333500).

666994 is a wasteful number, since it uses less digits than its factorization.

666994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333499.

The product of its digits is 69984, while the sum is 40.

The square root of 666994 is about 816.6970062392. The cubic root of 666994 is about 87.3723417345.

The spelling of 666994 in words is "six hundred sixty-six thousand, nine hundred ninety-four".