205285021 has 2 divisors, whose sum is σ = 205285022. Its totient is φ = 205285020.

The previous prime is 205285019. The next prime is 205285027. The reversal of 205285021 is 120582502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159112996 + 46172025 = 12614^2 + 6795^2 .

It is a cyclic number.

It is not a de Polignac number, because 205285021 - 2¹ = 205285019 is a prime.

Together with 205285019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205285027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102642510 + 102642511.

It is an arithmetic number, because the mean of its divisors is an integer number (102642511).

Almost surely, 2^205285021 is an apocalyptic number.

It is an amenable number.

205285021 is a deficient number, since it is larger than the sum of its proper divisors (1).

205285021 is an equidigital number, since it uses as much as digits as its factorization.

205285021 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 205285021 is about 14327.7709710897. The cubic root of 205285021 is about 589.9099939307.

The spelling of 205285021 in words is "two hundred five million, two hundred eighty-five thousand, twenty-one".