205638949 has 2 divisors, whose sum is σ = 205638950. Its totient is φ = 205638948.

The previous prime is 205638947. The next prime is 205638967. The reversal of 205638949 is 949836502.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 145684900 + 59954049 = 12070^2 + 7743^2 .

It is a cyclic number.

It is not a de Polignac number, because 205638949 - 2¹ = 205638947 is a prime.

Together with 205638947, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 205638899 and 205638908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205638941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102819474 + 102819475.

It is an arithmetic number, because the mean of its divisors is an integer number (102819475).

Almost surely, 2^205638949 is an apocalyptic number.

It is an amenable number.

205638949 is a deficient number, since it is larger than the sum of its proper divisors (1).

205638949 is an equidigital number, since it uses as much as digits as its factorization.

205638949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 466560, while the sum is 46.

The square root of 205638949 is about 14340.1167707937. The cubic root of 205638949 is about 590.2488168191.

The spelling of 205638949 in words is "two hundred five million, six hundred thirty-eight thousand, nine hundred forty-nine".