206331001561 has 4 divisors (see below), whose sum is σ = 206398854324. Its totient is φ = 206263148800.

The previous prime is 206331001537. The next prime is 206331001579. The reversal of 206331001561 is 165100133602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165100133602 = 2 ⋅82550066801.

It can be written as a sum of positive squares in 2 ways, for example, as 195944334336 + 10386667225 = 442656^2 + 101915^2 .

It is a cyclic number.

It is not a de Polignac number, because 206331001561 - 2¹¹ = 206330999513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206331001531) 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, 33921820 + ... + 33927901.

It is an arithmetic number, because the mean of its divisors is an integer number (51599713581).

Almost surely, 2^206331001561 is an apocalyptic number.

It is an amenable number.

206331001561 is a deficient number, since it is larger than the sum of its proper divisors (67852763).

206331001561 is an equidigital number, since it uses as much as digits as its factorization.

206331001561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67852762.

The product of its (nonzero) digits is 3240, while the sum is 28.

The spelling of 206331001561 in words is "two hundred six billion, three hundred thirty-one million, one thousand, five hundred sixty-one".