663257321 has 4 divisors (see below), whose sum is σ = 673156752. Its totient is φ = 653357892.

The previous prime is 663257311. The next prime is 663257359. The reversal of 663257321 is 123752366.

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 663257321 - 2²² = 659063017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (663257311) 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, 4949615 + ... + 4949748.

It is an arithmetic number, because the mean of its divisors is an integer number (168289188).

Almost surely, 2^663257321 is an apocalyptic number.

It is an amenable number.

663257321 is a deficient number, since it is larger than the sum of its proper divisors (9899431).

663257321 is an equidigital number, since it uses as much as digits as its factorization.

663257321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9899430.

The product of its digits is 45360, while the sum is 35.

The square root of 663257321 is about 25753.7826542044. The cubic root of 663257321 is about 872.0887500676.

The spelling of 663257321 in words is "six hundred sixty-three million, two hundred fifty-seven thousand, three hundred twenty-one".