666823 has 2 divisors, whose sum is σ = 666824. Its totient is φ = 666822.

The previous prime is 666821. The next prime is 666829. The reversal of 666823 is 328666.

666823 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 666823 - 2¹ = 666821 is a prime.

Together with 666821, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333411 + 333412.

It is an arithmetic number, because the mean of its divisors is an integer number (333412).

2⁶⁶⁶⁸²³ is an apocalyptic number.

666823 is a deficient number, since it is larger than the sum of its proper divisors (1).

666823 is an equidigital number, since it uses as much as digits as its factorization.

666823 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 31.

The square root of 666823 is about 816.5923095401. The cubic root of 666823 is about 87.3648744272.

It can be divided in two parts, 66 and 6823, that added together give a square (6889 = 83²).

The spelling of 666823 in words is "six hundred sixty-six thousand, eight hundred twenty-three".