665030221 has 2 divisors, whose sum is σ = 665030222. Its totient is φ = 665030220.

The previous prime is 665030189. The next prime is 665030237. The reversal of 665030221 is 122030566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 644906025 + 20124196 = 25395^2 + 4486^2 .

It is a cyclic number.

It is not a de Polignac number, because 665030221 - 2⁵ = 665030189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665034221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332515110 + 332515111.

It is an arithmetic number, because the mean of its divisors is an integer number (332515111).

Almost surely, 2^665030221 is an apocalyptic number.

It is an amenable number.

665030221 is a deficient number, since it is larger than the sum of its proper divisors (1).

665030221 is an equidigital number, since it uses as much as digits as its factorization.

665030221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 665030221 is about 25788.1798698551. The cubic root of 665030221 is about 872.8650956023.

Adding to 665030221 its reverse (122030566), we get a palindrome (787060787).

The spelling of 665030221 in words is "six hundred sixty-five million, thirty thousand, two hundred twenty-one".