77870809 has 2 divisors, whose sum is σ = 77870810. Its totient is φ = 77870808.

The previous prime is 77870803. The next prime is 77870839. The reversal of 77870809 is 90807877.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49280400 + 28590409 = 7020^2 + 5347^2 .

It is an emirp because it is prime and its reverse (90807877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 77870809 - 2⁵ = 77870777 is a prime.

It is not a weakly prime, because it can be changed into another prime (77870803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38935404 + 38935405.

It is an arithmetic number, because the mean of its divisors is an integer number (38935405).

Almost surely, 2^77870809 is an apocalyptic number.

It is an amenable number.

77870809 is a deficient number, since it is larger than the sum of its proper divisors (1).

77870809 is an equidigital number, since it uses as much as digits as its factorization.

77870809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 197568, while the sum is 46.

The square root of 77870809 is about 8824.4438351660. The cubic root of 77870809 is about 427.0298450584.

The spelling of 77870809 in words is "seventy-seven million, eight hundred seventy thousand, eight hundred nine".