85781398289 has 2 divisors, whose sum is σ = 85781398290. Its totient is φ = 85781398288.

The previous prime is 85781398271. The next prime is 85781398321. The reversal of 85781398289 is 98289318758.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80792377600 + 4989020689 = 284240^2 + 70633^2 .

It is a cyclic number.

It is not a de Polignac number, because 85781398289 - 2²⁰ = 85780349713 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 (85781398229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42890699144 + 42890699145.

It is an arithmetic number, because the mean of its divisors is an integer number (42890699145).

Almost surely, 2^85781398289 is an apocalyptic number.

It is an amenable number.

85781398289 is a deficient number, since it is larger than the sum of its proper divisors (1).

85781398289 is an equidigital number, since it uses as much as digits as its factorization.

85781398289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69672960, while the sum is 68.

The spelling of 85781398289 in words is "eighty-five billion, seven hundred eighty-one million, three hundred ninety-eight thousand, two hundred eighty-nine".