205121605 has 32 divisors (see below), whose sum is σ = 271514880. Its totient is φ = 147847680.

The previous prime is 205121603. The next prime is 205121617. The reversal of 205121605 is 506121502.

It is not a de Polignac number, because 205121605 - 2¹ = 205121603 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205121603) 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 31 ways as a sum of consecutive naturals, for example, 659400 + ... + 659710.

It is an arithmetic number, because the mean of its divisors is an integer number (8484840).

Almost surely, 2^205121605 is an apocalyptic number.

It is an amenable number.

205121605 is a deficient number, since it is larger than the sum of its proper divisors (66393275).

205121605 is a wasteful number, since it uses less digits than its factorization.

205121605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 541.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 205121605 is about 14322.0670644988. The cubic root of 205121605 is about 589.7534208529.

The spelling of 205121605 in words is "two hundred five million, one hundred twenty-one thousand, six hundred five".