78457109 has 2 divisors, whose sum is σ = 78457110. Its totient is φ = 78457108.

The previous prime is 78457097. The next prime is 78457111. The reversal of 78457109 is 90175487.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61622500 + 16834609 = 7850^2 + 4103^2 .

It is an emirp because it is prime and its reverse (90175487) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78457109 is a prime.

Together with 78457111, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78457609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39228554 + 39228555.

It is an arithmetic number, because the mean of its divisors is an integer number (39228555).

Almost surely, 2^78457109 is an apocalyptic number.

It is an amenable number.

78457109 is a deficient number, since it is larger than the sum of its proper divisors (1).

78457109 is an equidigital number, since it uses as much as digits as its factorization.

78457109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 70560, while the sum is 41.

The square root of 78457109 is about 8857.6017634572. The cubic root of 78457109 is about 428.0988886272.

The spelling of 78457109 in words is "seventy-eight million, four hundred fifty-seven thousand, one hundred nine".