208364561 has 2 divisors, whose sum is σ = 208364562. Its totient is φ = 208364560.

The previous prime is 208364543. The next prime is 208364587. The reversal of 208364561 is 165463802.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 181063936 + 27300625 = 13456^2 + 5225^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-208364561 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (208364161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104182280 + 104182281.

It is an arithmetic number, because the mean of its divisors is an integer number (104182281).

Almost surely, 2^208364561 is an apocalyptic number.

It is an amenable number.

208364561 is a deficient number, since it is larger than the sum of its proper divisors (1).

208364561 is an equidigital number, since it uses as much as digits as its factorization.

208364561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 208364561 is about 14434.8384473121. The cubic root of 208364561 is about 592.8451688628.

The spelling of 208364561 in words is "two hundred eight million, three hundred sixty-four thousand, five hundred sixty-one".