205506665 has 16 divisors (see below), whose sum is σ = 303518208. Its totient is φ = 130078656.

The previous prime is 205506647. The next prime is 205506667. The reversal of 205506665 is 566605502.

It is a cyclic number.

It is not a de Polignac number, because 205506665 - 2¹⁴ = 205490281 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (205506667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 225377 + ... + 226286.

It is an arithmetic number, because the mean of its divisors is an integer number (18969888).

Almost surely, 2^205506665 is an apocalyptic number.

It is an amenable number.

205506665 is a deficient number, since it is larger than the sum of its proper divisors (98011543).

205506665 is a wasteful number, since it uses less digits than its factorization.

205506665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451688.

The product of its (nonzero) digits is 54000, while the sum is 35.

The square root of 205506665 is about 14335.5036535170. The cubic root of 205506665 is about 590.1222240320.

The spelling of 205506665 in words is "two hundred five million, five hundred six thousand, six hundred sixty-five".