209087590861 has 2 divisors, whose sum is σ = 209087590862. Its totient is φ = 209087590860.

The previous prime is 209087590807. The next prime is 209087590879. The reversal of 209087590861 is 168095780902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 148586349961 + 60501240900 = 385469^2 + 245970^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209087590861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209087590801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104543795430 + 104543795431.

It is an arithmetic number, because the mean of its divisors is an integer number (104543795431).

Almost surely, 2^209087590861 is an apocalyptic number.

It is an amenable number.

209087590861 is a deficient number, since it is larger than the sum of its proper divisors (1).

209087590861 is an equidigital number, since it uses as much as digits as its factorization.

209087590861 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2177280, while the sum is 55.

The spelling of 209087590861 in words is "two hundred nine billion, eighty-seven million, five hundred ninety thousand, eight hundred sixty-one".