665698321 has 4 divisors (see below), whose sum is σ = 666299700. Its totient is φ = 665096944.

The previous prime is 665698301. The next prime is 665698331. The reversal of 665698321 is 123896566.

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

It can be written as a sum of positive squares in 2 ways, for example, as 83923921 + 581774400 = 9161^2 + 24120^2 .

It is a cyclic number.

It is not a de Polignac number, because 665698321 - 2²³ = 657309713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665698301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 299026 + ... + 301243.

It is an arithmetic number, because the mean of its divisors is an integer number (166574925).

Almost surely, 2^665698321 is an apocalyptic number.

It is an amenable number.

665698321 is a deficient number, since it is larger than the sum of its proper divisors (601379).

665698321 is a wasteful number, since it uses less digits than its factorization.

665698321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 601378.

The product of its digits is 466560, while the sum is 46.

The square root of 665698321 is about 25801.1302271819. The cubic root of 665698321 is about 873.1572958545.

The spelling of 665698321 in words is "six hundred sixty-five million, six hundred ninety-eight thousand, three hundred twenty-one".