628659221 has 2 divisors, whose sum is σ = 628659222. Its totient is φ = 628659220.

The previous prime is 628659217. The next prime is 628659223. The reversal of 628659221 is 122956826.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 584914225 + 43744996 = 24185^2 + 6614^2 .

It is a cyclic number.

It is not a de Polignac number, because 628659221 - 2² = 628659217 is a prime.

It is a super-2 number, since 2×628659221² = 790424832296653682, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 628659223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (628659223) 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 as a sum of consecutive naturals, namely, 314329610 + 314329611.

It is an arithmetic number, because the mean of its divisors is an integer number (314329611).

Almost surely, 2^628659221 is an apocalyptic number.

It is an amenable number.

628659221 is a deficient number, since it is larger than the sum of its proper divisors (1).

628659221 is an equidigital number, since it uses as much as digits as its factorization.

628659221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 103680, while the sum is 41.

The square root of 628659221 is about 25073.0776132488. The cubic root of 628659221 is about 856.6533088165.

The spelling of 628659221 in words is "six hundred twenty-eight million, six hundred fifty-nine thousand, two hundred twenty-one".