766801561 has 2 divisors, whose sum is σ = 766801562. Its totient is φ = 766801560.

The previous prime is 766801549. The next prime is 766801591. The reversal of 766801561 is 165108667.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 637865536 + 128936025 = 25256^2 + 11355^2 .

It is a cyclic number.

It is not a de Polignac number, because 766801561 - 2⁷ = 766801433 is a prime.

It is not a weakly prime, because it can be changed into another prime (766801591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 383400780 + 383400781.

It is an arithmetic number, because the mean of its divisors is an integer number (383400781).

Almost surely, 2^766801561 is an apocalyptic number.

It is an amenable number.

766801561 is a deficient number, since it is larger than the sum of its proper divisors (1).

766801561 is an equidigital number, since it uses as much as digits as its factorization.

766801561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60480, while the sum is 40.

The square root of 766801561 is about 27691.1820079967. The cubic root of 766801561 is about 915.2948022379.

The spelling of 766801561 in words is "seven hundred sixty-six million, eight hundred one thousand, five hundred sixty-one".