205778997 has 12 divisors (see below), whose sum is σ = 297704160. Its totient is φ = 136970088.

The previous prime is 205778977. The next prime is 205779011. The reversal of 205778997 is 799877502.

It is not a de Polignac number, because 205778997 - 2⁶ = 205778933 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205778917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11847 + ... + 23492.

It is an arithmetic number, because the mean of its divisors is an integer number (24808680).

Almost surely, 2^205778997 is an apocalyptic number.

It is an amenable number.

205778997 is a deficient number, since it is larger than the sum of its proper divisors (91925163).

205778997 is a wasteful number, since it uses less digits than its factorization.

205778997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35992 (or 35989 counting only the distinct ones).

The product of its (nonzero) digits is 2222640, while the sum is 54.

The square root of 205778997 is about 14344.9990240502. Note that the first 3 decimals coincide. The cubic root of 205778997 is about 590.3827804290.

The spelling of 205778997 in words is "two hundred five million, seven hundred seventy-eight thousand, nine hundred ninety-seven".