668864509 has 4 divisors (see below), whose sum is σ = 669114304. Its totient is φ = 668614716.

The previous prime is 668864501. The next prime is 668864513. The reversal of 668864509 is 905468866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 668864509 - 2³ = 668864501 is a prime.

It is a super-2 number, since 2×668864509² = 894759462799622162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668864501) 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, 120837 + ... + 126250.

It is an arithmetic number, because the mean of its divisors is an integer number (167278576).

Almost surely, 2^668864509 is an apocalyptic number.

It is an amenable number.

668864509 is a deficient number, since it is larger than the sum of its proper divisors (249795).

668864509 is a wasteful number, since it uses less digits than its factorization.

668864509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249794.

The product of its (nonzero) digits is 2488320, while the sum is 52.

The square root of 668864509 is about 25862.4149877771. The cubic root of 668864509 is about 874.5394077678.

The spelling of 668864509 in words is "six hundred sixty-eight million, eight hundred sixty-four thousand, five hundred nine".