206561091 has 32 divisors (see below), whose sum is σ = 323665920. Its totient is φ = 115869600.

The previous prime is 206561077. The next prime is 206561107. The reversal of 206561091 is 190165602.

It is not a de Polignac number, because 206561091 - 2¹¹ = 206559043 is a prime.

It is a super-2 number, since 2×206561091² = 85334968630220562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (206561011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19140 + ... + 27918.

It is an arithmetic number, because the mean of its divisors is an integer number (10114560).

Almost surely, 2^206561091 is an apocalyptic number.

206561091 is a deficient number, since it is larger than the sum of its proper divisors (117104829).

206561091 is a wasteful number, since it uses less digits than its factorization.

206561091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8847.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 206561091 is about 14372.2333337585. The cubic root of 206561091 is about 591.1297810216.

The spelling of 206561091 in words is "two hundred six million, five hundred sixty-one thousand, ninety-one".