78838709 has 2 divisors, whose sum is σ = 78838710. Its totient is φ = 78838708.

The previous prime is 78838637. The next prime is 78838717. The reversal of 78838709 is 90783887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 44849809 + 33988900 = 6697^2 + 5830^2 .

It is an emirp because it is prime and its reverse (90783887) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78838709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78838769) 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, 39419354 + 39419355.

It is an arithmetic number, because the mean of its divisors is an integer number (39419355).

Almost surely, 2^78838709 is an apocalyptic number.

It is an amenable number.

78838709 is a deficient number, since it is larger than the sum of its proper divisors (1).

78838709 is an equidigital number, since it uses as much as digits as its factorization.

78838709 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 677376, while the sum is 50.

The square root of 78838709 is about 8879.1164537920. The cubic root of 78838709 is about 428.7918294237.

The spelling of 78838709 in words is "seventy-eight million, eight hundred thirty-eight thousand, seven hundred nine".