665221393 has 4 divisors (see below), whose sum is σ = 665452980. Its totient is φ = 664989808.

The previous prime is 665221327. The next prime is 665221411. The reversal of 665221393 is 393122566.

665221393 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 330221584 + 334999809 = 18172^2 + 18303^2 .

It is a cyclic number.

It is not a de Polignac number, because 665221393 - 2¹³ = 665213201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665221303) 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, 111430 + ... + 117247.

It is an arithmetic number, because the mean of its divisors is an integer number (166363245).

Almost surely, 2^665221393 is an apocalyptic number.

It is an amenable number.

665221393 is a deficient number, since it is larger than the sum of its proper divisors (231587).

665221393 is a wasteful number, since it uses less digits than its factorization.

665221393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231586.

The product of its digits is 58320, while the sum is 37.

The square root of 665221393 is about 25791.8861853878. The cubic root of 665221393 is about 872.9487265782.

The spelling of 665221393 in words is "six hundred sixty-five million, two hundred twenty-one thousand, three hundred ninety-three".