20558221 has 2 divisors, whose sum is σ = 20558222. Its totient is φ = 20558220.

The previous prime is 20558207. The next prime is 20558233. The reversal of 20558221 is 12285502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11492100 + 9066121 = 3390^2 + 3011^2 .

It is a cyclic number.

It is not a de Polignac number, because 20558221 - 2⁵ = 20558189 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20558621) 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, 10279110 + 10279111.

It is an arithmetic number, because the mean of its divisors is an integer number (10279111).

Almost surely, 2^20558221 is an apocalyptic number.

It is an amenable number.

20558221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20558221 is an equidigital number, since it uses as much as digits as its factorization.

20558221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 20558221 is about 4534.1174444427. The cubic root of 20558221 is about 273.9440319380.

The spelling of 20558221 in words is "twenty million, five hundred fifty-eight thousand, two hundred twenty-one".