205641990 has 40 divisors (see below), whose sum is σ = 552950640. Its totient is φ = 54837648.

The previous prime is 205641973. The next prime is 205641991. The reversal of 205641990 is 99146502.

205641990 is a `hidden beast` number, since 2 + 0 + 5 + 641 + 9 + 9 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205641991) 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 in 19 ways as a sum of consecutive naturals, for example, 126130 + ... + 127749.

It is an arithmetic number, because the mean of its divisors is an integer number (13823766).

Almost surely, 2^205641990 is an apocalyptic number.

205641990 is an abundant number, since it is smaller than the sum of its proper divisors (347308650).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

205641990 is a wasteful number, since it uses less digits than its factorization.

205641990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253898 (or 253889 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 205641990 is about 14340.2228016164. Note that the first 3 decimals coincide. The cubic root of 205641990 is about 590.2517263487.

The spelling of 205641990 in words is "two hundred five million, six hundred forty-one thousand, nine hundred ninety".