20543221 has 2 divisors, whose sum is σ = 20543222. Its totient is φ = 20543220.

The previous prime is 20543197. The next prime is 20543233. The reversal of 20543221 is 12234502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16112196 + 4431025 = 4014^2 + 2105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20543221 - 2⁷ = 20543093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20543321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10271610 + 10271611.

It is an arithmetic number, because the mean of its divisors is an integer number (10271611).

Almost surely, 2^20543221 is an apocalyptic number.

It is an amenable number.

20543221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20543221 is an equidigital number, since it uses as much as digits as its factorization.

20543221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20543221 is about 4532.4630169478. The cubic root of 20543221 is about 273.8773893317.

Adding to 20543221 its reverse (12234502), we get a palindrome (32777723).

The spelling of 20543221 in words is "twenty million, five hundred forty-three thousand, two hundred twenty-one".