666890 has 24 divisors (see below), whose sum is σ = 1397412. Its totient is φ = 228480.

The previous prime is 666889. The next prime is 666901. The reversal of 666890 is 98666.

It can be written as a sum of positive squares in 2 ways, for example, as 625681 + 41209 = 791^2 + 203^2 .

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 666890.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 191 + ... + 1170.

2⁶⁶⁶⁸⁹⁰ is an apocalyptic number.

666890 is an abundant number, since it is smaller than the sum of its proper divisors (730522).

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

666890 is a wasteful number, since it uses less digits than its factorization.

666890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1382 (or 1375 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 666890 is about 816.6333326530. The cubic root of 666890 is about 87.3678003664.

The spelling of 666890 in words is "six hundred sixty-six thousand, eight hundred ninety".