20555205221 has 2 divisors, whose sum is σ = 20555205222. Its totient is φ = 20555205220.

The previous prime is 20555205217. The next prime is 20555205239. The reversal of 20555205221 is 12250255502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17487153121 + 3068052100 = 132239^2 + 55390^2 .

It is a cyclic number.

It is not a de Polignac number, because 20555205221 - 2² = 20555205217 is a prime.

It is a Sophie Germain 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 (20555205241) 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, 10277602610 + 10277602611.

It is an arithmetic number, because the mean of its divisors is an integer number (10277602611).

Almost surely, 2^20555205221 is an apocalyptic number.

It is an amenable number.

20555205221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20555205221 is an equidigital number, since it uses as much as digits as its factorization.

20555205221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10000, while the sum is 29.

The spelling of 20555205221 in words is "twenty billion, five hundred fifty-five million, two hundred five thousand, two hundred twenty-one".