865219109 has 2 divisors, whose sum is σ = 865219110. Its totient is φ = 865219108.

The previous prime is 865219073. The next prime is 865219127. The reversal of 865219109 is 901912568.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 823977025 + 41242084 = 28705^2 + 6422^2 .

It is a cyclic number.

It is not a de Polignac number, because 865219109 - 2²⁰ = 864170533 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (865219189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432609554 + 432609555.

It is an arithmetic number, because the mean of its divisors is an integer number (432609555).

Almost surely, 2^865219109 is an apocalyptic number.

It is an amenable number.

865219109 is a deficient number, since it is larger than the sum of its proper divisors (1).

865219109 is an equidigital number, since it uses as much as digits as its factorization.

865219109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 865219109 is about 29414.6070685977. The cubic root of 865219109 is about 952.8883870657. Note that the first 3 decimals are identical.

The spelling of 865219109 in words is "eight hundred sixty-five million, two hundred nineteen thousand, one hundred nine".