208556261 has 2 divisors, whose sum is σ = 208556262. Its totient is φ = 208556260.

The previous prime is 208556207. The next prime is 208556263. The reversal of 208556261 is 162655802.

208556261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208253761 + 302500 = 14431^2 + 550^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-208556261 is a prime.

It is a Sophie Germain prime.

Together with 208556263, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208556263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104278130 + 104278131.

It is an arithmetic number, because the mean of its divisors is an integer number (104278131).

Almost surely, 2^208556261 is an apocalyptic number.

It is an amenable number.

208556261 is a deficient number, since it is larger than the sum of its proper divisors (1).

208556261 is an equidigital number, since it uses as much as digits as its factorization.

208556261 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28800, while the sum is 35.

The square root of 208556261 is about 14441.4771058919. The cubic root of 208556261 is about 593.0269233530.

The spelling of 208556261 in words is "two hundred eight million, five hundred fifty-six thousand, two hundred sixty-one".