865864435721 has 2 divisors, whose sum is σ = 865864435722. Its totient is φ = 865864435720.

The previous prime is 865864435673. The next prime is 865864435769. The reversal of 865864435721 is 127534468568.

It is a balanced prime because it is at equal distance from previous prime (865864435673) and next prime (865864435769).

It can be written as a sum of positive squares in only one way, i.e., 781915747600 + 83948688121 = 884260^2 + 289739^2 .

It is a cyclic number.

It is not a de Polignac number, because 865864435721 - 2¹⁴ = 865864419337 is a prime.

It is not a weakly prime, because it can be changed into another prime (865864435321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432932217860 + 432932217861.

It is an arithmetic number, because the mean of its divisors is an integer number (432932217861).

Almost surely, 2^865864435721 is an apocalyptic number.

It is an amenable number.

865864435721 is a deficient number, since it is larger than the sum of its proper divisors (1).

865864435721 is an equidigital number, since it uses as much as digits as its factorization.

865864435721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38707200, while the sum is 59.

The spelling of 865864435721 in words is "eight hundred sixty-five billion, eight hundred sixty-four million, four hundred thirty-five thousand, seven hundred twenty-one".