864806561 has 2 divisors, whose sum is σ = 864806562. Its totient is φ = 864806560.

The previous prime is 864806549. The next prime is 864806567. The reversal of 864806561 is 165608468.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 839202961 + 25603600 = 28969^2 + 5060^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-864806561 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (864806567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432403280 + 432403281.

It is an arithmetic number, because the mean of its divisors is an integer number (432403281).

Almost surely, 2^864806561 is an apocalyptic number.

It is an amenable number.

864806561 is a deficient number, since it is larger than the sum of its proper divisors (1).

864806561 is an equidigital number, since it uses as much as digits as its factorization.

864806561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 276480, while the sum is 44.

The square root of 864806561 is about 29407.5935941722. The cubic root of 864806561 is about 952.7369130282.

The spelling of 864806561 in words is "eight hundred sixty-four million, eight hundred six thousand, five hundred sixty-one".