764643661 has 2 divisors, whose sum is σ = 764643662. Its totient is φ = 764643660.

The previous prime is 764643641. The next prime is 764643689. The reversal of 764643661 is 166346467.

764643661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 628454761 + 136188900 = 25069^2 + 11670^2 .

It is a cyclic number.

It is not a de Polignac number, because 764643661 - 2¹¹ = 764641613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (764643641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 382321830 + 382321831.

It is an arithmetic number, because the mean of its divisors is an integer number (382321831).

Almost surely, 2^764643661 is an apocalyptic number.

It is an amenable number.

764643661 is a deficient number, since it is larger than the sum of its proper divisors (1).

764643661 is an equidigital number, since it uses as much as digits as its factorization.

764643661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 435456, while the sum is 43.

The square root of 764643661 is about 27652.1908896926. The cubic root of 764643661 is about 914.4354011372.

The spelling of 764643661 in words is "seven hundred sixty-four million, six hundred forty-three thousand, six hundred sixty-one".