78425909 has 2 divisors, whose sum is σ = 78425910. Its totient is φ = 78425908.

The previous prime is 78425873. The next prime is 78425911. The reversal of 78425909 is 90952487.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78411025 + 14884 = 8855^2 + 122^2 .

It is a cyclic number.

It is not a de Polignac number, because 78425909 - 2¹² = 78421813 is a prime.

Together with 78425911, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_4582898 and since 78425909 and 4582898 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78425909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78425509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39212954 + 39212955.

It is an arithmetic number, because the mean of its divisors is an integer number (39212955).

Almost surely, 2^78425909 is an apocalyptic number.

It is an amenable number.

78425909 is a deficient number, since it is larger than the sum of its proper divisors (1).

78425909 is an equidigital number, since it uses as much as digits as its factorization.

78425909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 181440, while the sum is 44.

The square root of 78425909 is about 8855.8403892572. The cubic root of 78425909 is about 428.0421338117.

The spelling of 78425909 in words is "seventy-eight million, four hundred twenty-five thousand, nine hundred nine".