664206523 has 4 divisors (see below), whose sum is σ = 664390168. Its totient is φ = 664022880.

The previous prime is 664206497. The next prime is 664206559. The reversal of 664206523 is 325602466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664206523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664206563) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 86286 + ... + 93667.

It is an arithmetic number, because the mean of its divisors is an integer number (166097542).

Almost surely, 2^664206523 is an apocalyptic number.

664206523 is a deficient number, since it is larger than the sum of its proper divisors (183645).

664206523 is a wasteful number, since it uses less digits than its factorization.

664206523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183644.

The product of its (nonzero) digits is 51840, while the sum is 34.

The square root of 664206523 is about 25772.2044652762. The cubic root of 664206523 is about 872.5045735017.

Adding to 664206523 its reverse (325602466), we get a palindrome (989808989).

The spelling of 664206523 in words is "six hundred sixty-four million, two hundred six thousand, five hundred twenty-three".