666523 has 16 divisors (see below), whose sum is σ = 806400. Its totient is φ = 542880.

The previous prime is 666511. The next prime is 666527. The reversal of 666523 is 325666.

It is a de Polignac number, because none of the positive numbers 2^k-666523 is a prime.

It is a Duffinian number.

Its product of digits (6480) is a multiple of the sum of its prime divisors (162).

It is a junction number, because it is equal to n+sod(n) for n = 666491 and 666500.

It is not an unprimeable number, because it can be changed into a prime (666527) 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 15 ways as a sum of consecutive naturals, for example, 8398 + ... + 8476.

It is an arithmetic number, because the mean of its divisors is an integer number (50400).

2⁶⁶⁶⁵²³ is an apocalyptic number.

666523 is a deficient number, since it is larger than the sum of its proper divisors (139877).

666523 is a wasteful number, since it uses less digits than its factorization.

666523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162.

The product of its digits is 6480, while the sum is 28.

The square root of 666523 is about 816.4085986808. The cubic root of 666523 is about 87.3517708031.

The spelling of 666523 in words is "six hundred sixty-six thousand, five hundred twenty-three".