208665093781 has 2 divisors, whose sum is σ = 208665093782. Its totient is φ = 208665093780.

The previous prime is 208665093739. The next prime is 208665093803. The reversal of 208665093781 is 187390566802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 109922087025 + 98743006756 = 331545^2 + 314234^2 .

It is a cyclic number.

It is not a de Polignac number, because 208665093781 - 2⁹ = 208665093269 is a prime.

It is a super-2 number, since 2×208665093781² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (208663093781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104332546890 + 104332546891.

It is an arithmetic number, because the mean of its divisors is an integer number (104332546891).

Almost surely, 2^208665093781 is an apocalyptic number.

It is an amenable number.

208665093781 is a deficient number, since it is larger than the sum of its proper divisors (1).

208665093781 is an equidigital number, since it uses as much as digits as its factorization.

208665093781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4354560, while the sum is 55.

The spelling of 208665093781 in words is "two hundred eight billion, six hundred sixty-five million, ninety-three thousand, seven hundred eighty-one".