206660591 has 4 divisors (see below), whose sum is σ = 209491632. Its totient is φ = 203829552.

The previous prime is 206660569. The next prime is 206660593. The reversal of 206660591 is 195066602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 206660591 - 2¹⁸ = 206398447 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 (206660593) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1415411 + ... + 1415556.

It is an arithmetic number, because the mean of its divisors is an integer number (52372908).

Almost surely, 2^206660591 is an apocalyptic number.

206660591 is a deficient number, since it is larger than the sum of its proper divisors (2831041).

206660591 is an equidigital number, since it uses as much as digits as its factorization.

206660591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2831040.

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

The square root of 206660591 is about 14375.6944527908. The cubic root of 206660591 is about 591.2246810685.

The spelling of 206660591 in words is "two hundred six million, six hundred sixty thousand, five hundred ninety-one".