205021661 has 16 divisors (see below), whose sum is σ = 226431744. Its totient is φ = 184451904.

The previous prime is 205021657. The next prime is 205021667. The reversal of 205021661 is 166120502.

205021661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 205021661 - 2² = 205021657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205021667) 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, 187031 + ... + 188123.

It is an arithmetic number, because the mean of its divisors is an integer number (14151984).

Almost surely, 2^205021661 is an apocalyptic number.

It is an amenable number.

205021661 is a deficient number, since it is larger than the sum of its proper divisors (21410083).

205021661 is a wasteful number, since it uses less digits than its factorization.

205021661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1460.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 205021661 is about 14318.5774782274. The cubic root of 205021661 is about 589.6576209467.

The spelling of 205021661 in words is "two hundred five million, twenty-one thousand, six hundred sixty-one".