861385009 has 2 divisors, whose sum is σ = 861385010. Its totient is φ = 861385008.

The previous prime is 861384977. The next prime is 861385033. The reversal of 861385009 is 900583168.

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., 737285409 + 124099600 = 27153^2 + 11140^2 .

It is a cyclic number.

It is not a de Polignac number, because 861385009 - 2⁵ = 861384977 is a prime.

It is not a weakly prime, because it can be changed into another prime (861385079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430692504 + 430692505.

It is an arithmetic number, because the mean of its divisors is an integer number (430692505).

Almost surely, 2^861385009 is an apocalyptic number.

It is an amenable number.

861385009 is a deficient number, since it is larger than the sum of its proper divisors (1).

861385009 is an equidigital number, since it uses as much as digits as its factorization.

861385009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 40.

The square root of 861385009 is about 29349.3613048053. The cubic root of 861385009 is about 951.4787713709.

The spelling of 861385009 in words is "eight hundred sixty-one million, three hundred eighty-five thousand, nine".