205207021 has 2 divisors, whose sum is σ = 205207022. Its totient is φ = 205207020.

The previous prime is 205207001. The next prime is 205207027. The reversal of 205207021 is 120702502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 149181796 + 56025225 = 12214^2 + 7485^2 .

It is a cyclic number.

It is not a de Polignac number, because 205207021 - 2⁷ = 205206893 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205207021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205207027) 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, 102603510 + 102603511.

It is an arithmetic number, because the mean of its divisors is an integer number (102603511).

Almost surely, 2^205207021 is an apocalyptic number.

It is an amenable number.

205207021 is a deficient number, since it is larger than the sum of its proper divisors (1).

205207021 is an equidigital number, since it uses as much as digits as its factorization.

205207021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 205207021 is about 14325.0487259206. The cubic root of 205207021 is about 589.8352704913.

Adding to 205207021 its reverse (120702502), we get a palindrome (325909523).

The spelling of 205207021 in words is "two hundred five million, two hundred seven thousand, twenty-one".