205661906 has 8 divisors (see below), whose sum is σ = 321905664. Its totient is φ = 98360020.

The previous prime is 205661899. The next prime is 205661917. The reversal of 205661906 is 609166502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2235410 + ... + 2235501.

It is an arithmetic number, because the mean of its divisors is an integer number (40238208).

Almost surely, 2^205661906 is an apocalyptic number.

205661906 is a deficient number, since it is larger than the sum of its proper divisors (116243758).

205661906 is a wasteful number, since it uses less digits than its factorization.

205661906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4470936.

The product of its (nonzero) digits is 19440, while the sum is 35.

The square root of 205661906 is about 14340.9171952145. The cubic root of 205661906 is about 590.2707806186.

The spelling of 205661906 in words is "two hundred five million, six hundred sixty-one thousand, nine hundred six".