664791309 has 72 divisors (see below), whose sum is σ = 1212731520. Its totient is φ = 341724096.

The previous prime is 664791299. The next prime is 664791319. The reversal of 664791309 is 903197466.

It is an interprime number because it is at equal distance from previous prime (664791299) and next prime (664791319).

It is not a de Polignac number, because 664791309 - 2¹¹ = 664789261 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664791319) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1514112 + ... + 1514550.

Almost surely, 2^664791309 is an apocalyptic number.

It is an amenable number.

664791309 is a deficient number, since it is larger than the sum of its proper divisors (547940211).

664791309 is a wasteful number, since it uses less digits than its factorization.

664791309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 551 (or 505 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 45.

The square root of 664791309 is about 25783.5472540145. The cubic root of 664791309 is about 872.7605575344.

The spelling of 664791309 in words is "six hundred sixty-four million, seven hundred ninety-one thousand, three hundred nine".