205642697 has 4 divisors (see below), whose sum is σ = 221461380. Its totient is φ = 189824016.

The previous prime is 205642691. The next prime is 205642721. The reversal of 205642697 is 796246502.

205642697 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 796246502 = 2 ⋅398123251.

It can be written as a sum of positive squares in 2 ways, for example, as 34058896 + 171583801 = 5836^2 + 13099^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-205642697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (205642691) 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, 7909322 + ... + 7909347.

It is an arithmetic number, because the mean of its divisors is an integer number (55365345).

Almost surely, 2^205642697 is an apocalyptic number.

It is an amenable number.

205642697 is a deficient number, since it is larger than the sum of its proper divisors (15818683).

205642697 is a wasteful number, since it uses less digits than its factorization.

205642697 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15818682.

The product of its (nonzero) digits is 181440, while the sum is 41.

The square root of 205642697 is about 14340.2474525372. The cubic root of 205642697 is about 590.2524027791.

The spelling of 205642697 in words is "two hundred five million, six hundred forty-two thousand, six hundred ninety-seven".