666990 has 24 divisors (see below), whose sum is σ = 1734408. Its totient is φ = 177840.

The previous prime is 666989. The next prime is 667013. The reversal of 666990 is 99666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3616 + ... + 3795.

It is an arithmetic number, because the mean of its divisors is an integer number (72267).

2⁶⁶⁶⁹⁹⁰ is an apocalyptic number.

666990 is an abundant number, since it is smaller than the sum of its proper divisors (1067418).

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

666990 is a wasteful number, since it uses less digits than its factorization.

666990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7424 (or 7421 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 36.

The square root of 666990 is about 816.6945573469. The cubic root of 666990 is about 87.3721670752.

Adding to 666990 its product of nonzero digits (17496), we get a palindrome (684486).

It can be divided in two parts, 66 and 6990, that added together give a square (7056 = 84²).

The spelling of 666990 in words is "six hundred sixty-six thousand, nine hundred ninety".