206626561 has 2 divisors, whose sum is σ = 206626562. Its totient is φ = 206626560.

The previous prime is 206626559. The next prime is 206626627. The reversal of 206626561 is 165626602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 174636225 + 31990336 = 13215^2 + 5656^2 .

It is a cyclic number.

It is not a de Polignac number, because 206626561 - 2¹ = 206626559 is a prime.

Together with 206626559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (206626531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103313280 + 103313281.

It is an arithmetic number, because the mean of its divisors is an integer number (103313281).

Almost surely, 2^206626561 is an apocalyptic number.

It is an amenable number.

206626561 is a deficient number, since it is larger than the sum of its proper divisors (1).

206626561 is an equidigital number, since it uses as much as digits as its factorization.

206626561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 206626561 is about 14374.5108090676. The cubic root of 206626561 is about 591.1922277268.

The spelling of 206626561 in words is "two hundred six million, six hundred twenty-six thousand, five hundred sixty-one".