555660221 has 2 divisors, whose sum is σ = 555660222. Its totient is φ = 555660220.

The previous prime is 555660199. The next prime is 555660223. The reversal of 555660221 is 122066555.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 415711321 + 139948900 = 20389^2 + 11830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-555660221 is a prime.

It is a Sophie Germain prime.

Together with 555660223, 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 (555660223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 277830110 + 277830111.

It is an arithmetic number, because the mean of its divisors is an integer number (277830111).

Almost surely, 2^555660221 is an apocalyptic number.

It is an amenable number.

555660221 is a deficient number, since it is larger than the sum of its proper divisors (1).

555660221 is an equidigital number, since it uses as much as digits as its factorization.

555660221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18000, while the sum is 32.

The square root of 555660221 is about 23572.4462243527. The cubic root of 555660221 is about 822.1223136384.

The spelling of 555660221 in words is "five hundred fifty-five million, six hundred sixty thousand, two hundred twenty-one".