205513921 has 2 divisors, whose sum is σ = 205513922. Its totient is φ = 205513920.

The previous prime is 205513897. The next prime is 205513963. The reversal of 205513921 is 129315502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199939600 + 5574321 = 14140^2 + 2361^2 .

It is a cyclic number.

It is not a de Polignac number, because 205513921 - 2²¹ = 203416769 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 205513921.

It is not a weakly prime, because it can be changed into another prime (205513421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102756960 + 102756961.

It is an arithmetic number, because the mean of its divisors is an integer number (102756961).

Almost surely, 2^205513921 is an apocalyptic number.

It is an amenable number.

205513921 is a deficient number, since it is larger than the sum of its proper divisors (1).

205513921 is an equidigital number, since it uses as much as digits as its factorization.

205513921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2700, while the sum is 28.

The square root of 205513921 is about 14335.7567292417. The cubic root of 205513921 is about 590.1291692674.

The spelling of 205513921 in words is "two hundred five million, five hundred thirteen thousand, nine hundred twenty-one".