666550 has 12 divisors (see below), whose sum is σ = 1239876. Its totient is φ = 266600.

The previous prime is 666541. The next prime is 666557. The reversal of 666550 is 55666.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666557) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 6616 + ... + 6715.

It is an arithmetic number, because the mean of its divisors is an integer number (103323).

2⁶⁶⁶⁵⁵⁰ is an apocalyptic number.

666550 is a deficient number, since it is larger than the sum of its proper divisors (573326).

666550 is a wasteful number, since it uses less digits than its factorization.

666550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13343 (or 13338 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 666550 is about 816.4251343510. The cubic root of 666550 is about 87.3529502903.

The spelling of 666550 in words is "six hundred sixty-six thousand, five hundred fifty".