205643939 has 2 divisors, whose sum is σ = 205643940. Its totient is φ = 205643938.

The previous prime is 205643927. The next prime is 205643953. The reversal of 205643939 is 939346502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 205643939 - 2¹² = 205639843 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 205643896 and 205643905.

It is not a weakly prime, because it can be changed into another prime (205643909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102821969 + 102821970.

It is an arithmetic number, because the mean of its divisors is an integer number (102821970).

Almost surely, 2^205643939 is an apocalyptic number.

205643939 is a deficient number, since it is larger than the sum of its proper divisors (1).

205643939 is an equidigital number, since it uses as much as digits as its factorization.

205643939 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 174960, while the sum is 41.

The square root of 205643939 is about 14340.2907571639. The cubic root of 205643939 is about 590.2535910732.

The spelling of 205643939 in words is "two hundred five million, six hundred forty-three thousand, nine hundred thirty-nine".