78999691 has 2 divisors, whose sum is σ = 78999692. Its totient is φ = 78999690.

The previous prime is 78999689. The next prime is 78999707. The reversal of 78999691 is 19699987.

It is a weak prime.

It is an emirp because it is prime and its reverse (19699987) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78999691 - 2¹ = 78999689 is a prime.

Together with 78999689, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (78999611) 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, 39499845 + 39499846.

It is an arithmetic number, because the mean of its divisors is an integer number (39499846).

Almost surely, 2^78999691 is an apocalyptic number.

78999691 is a deficient number, since it is larger than the sum of its proper divisors (1).

78999691 is an equidigital number, since it uses as much as digits as its factorization.

78999691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2204496, while the sum is 58.

The square root of 78999691 is about 8888.1770346905. The cubic root of 78999691 is about 429.0834832632.

The spelling of 78999691 in words is "seventy-eight million, nine hundred ninety-nine thousand, six hundred ninety-one".