666618 has 8 divisors (see below), whose sum is σ = 1333248. Its totient is φ = 222204.

The previous prime is 666607. The next prime is 666637. The reversal of 666618 is 816666.

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

666618 is an admirable number.

It is a nialpdrome in base 7.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55546 + ... + 55557.

It is an arithmetic number, because the mean of its divisors is an integer number (166656).

2⁶⁶⁶⁶¹⁸ is an apocalyptic number.

666618 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

666618 is a wasteful number, since it uses less digits than its factorization.

666618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111108.

The product of its digits is 10368, while the sum is 33.

The square root of 666618 is about 816.4667782586. The cubic root of 666618 is about 87.3559207094.

The spelling of 666618 in words is "six hundred sixty-six thousand, six hundred eighteen".