666418 has 4 divisors (see below), whose sum is σ = 999630. Its totient is φ = 333208.

The previous prime is 666403. The next prime is 666427. The reversal of 666418 is 814666.

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

It can be written as a sum of positive squares in only one way, i.e., 644809 + 21609 = 803^2 + 147^2 .

It is a super-2 number, since 2×666418² = 888225901448, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 666418.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166603 + ... + 166606.

2⁶⁶⁶⁴¹⁸ is an apocalyptic number.

666418 is a deficient number, since it is larger than the sum of its proper divisors (333212).

666418 is a wasteful number, since it uses less digits than its factorization.

666418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333211.

The product of its digits is 6912, while the sum is 31.

The square root of 666418 is about 816.3442901129. The cubic root of 666418 is about 87.3471836058.

The spelling of 666418 in words is "six hundred sixty-six thousand, four hundred eighteen".