728678809 has 2 divisors, whose sum is σ = 728678810. Its totient is φ = 728678808.

The previous prime is 728678807. The next prime is 728678827. The reversal of 728678809 is 908876827.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 716097600 + 12581209 = 26760^2 + 3547^2 .

It is an emirp because it is prime and its reverse (908876827) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 728678809 - 2¹ = 728678807 is a prime.

Together with 728678807, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 728678809.

It is not a weakly prime, because it can be changed into another prime (728678807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 364339404 + 364339405.

It is an arithmetic number, because the mean of its divisors is an integer number (364339405).

Almost surely, 2^728678809 is an apocalyptic number.

It is an amenable number.

728678809 is a deficient number, since it is larger than the sum of its proper divisors (1).

728678809 is an equidigital number, since it uses as much as digits as its factorization.

728678809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2709504, while the sum is 55.

The square root of 728678809 is about 26994.0513632170. The cubic root of 728678809 is about 899.8678032169.

The spelling of 728678809 in words is "seven hundred twenty-eight million, six hundred seventy-eight thousand, eight hundred nine".