206505643 has 4 divisors (see below), whose sum is σ = 211542408. Its totient is φ = 201468880.

The previous prime is 206505631. The next prime is 206505653. The reversal of 206505643 is 346505602.

206505643 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: 346505602 = 2 ⋅173252801.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206505643 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206505653) 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, 2518321 + ... + 2518402.

It is an arithmetic number, because the mean of its divisors is an integer number (52885602).

Almost surely, 2^206505643 is an apocalyptic number.

206505643 is a deficient number, since it is larger than the sum of its proper divisors (5036765).

206505643 is an equidigital number, since it uses as much as digits as its factorization.

206505643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5036764.

The product of its (nonzero) digits is 21600, while the sum is 31.

The square root of 206505643 is about 14370.3042069401. The cubic root of 206505643 is about 591.0768831965.

The spelling of 206505643 in words is "two hundred six million, five hundred five thousand, six hundred forty-three".