664784840861 has 2 divisors, whose sum is σ = 664784840862. Its totient is φ = 664784840860.

The previous prime is 664784840849. The next prime is 664784840873. The reversal of 664784840861 is 168048487466.

It is a balanced prime because it is at equal distance from previous prime (664784840849) and next prime (664784840873).

It can be written as a sum of positive squares in only one way, i.e., 632350992025 + 32433848836 = 795205^2 + 180094^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664784840861 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 664784840794 and 664784840803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664784140861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332392420430 + 332392420431.

It is an arithmetic number, because the mean of its divisors is an integer number (332392420431).

Almost surely, 2^664784840861 is an apocalyptic number.

It is an amenable number.

664784840861 is a deficient number, since it is larger than the sum of its proper divisors (1).

664784840861 is an equidigital number, since it uses as much as digits as its factorization.

664784840861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 49545216, while the sum is 62.

The spelling of 664784840861 in words is "six hundred sixty-four billion, seven hundred eighty-four million, eight hundred forty thousand, eight hundred sixty-one".