663020321 has 4 divisors (see below), whose sum is σ = 663092100. Its totient is φ = 662948544.

The previous prime is 663020299. The next prime is 663020329. The reversal of 663020321 is 123020366.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 24750625 + 638269696 = 4975^2 + 25264^2 .

It is a cyclic number.

It is not a de Polignac number, because 663020321 - 2²² = 658826017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (663020329) 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, 19556 + ... + 41333.

It is an arithmetic number, because the mean of its divisors is an integer number (165773025).

Almost surely, 2^663020321 is an apocalyptic number.

It is an amenable number.

663020321 is a deficient number, since it is larger than the sum of its proper divisors (71779).

663020321 is a wasteful number, since it uses less digits than its factorization.

663020321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71778.

The product of its (nonzero) digits is 1296, while the sum is 23.

The square root of 663020321 is about 25749.1809772661. The cubic root of 663020321 is about 871.9848639638.

Adding to 663020321 its reverse (123020366), we get a palindrome (786040687).

The spelling of 663020321 in words is "six hundred sixty-three million, twenty thousand, three hundred twenty-one".