78831691 has 2 divisors, whose sum is σ = 78831692. Its totient is φ = 78831690.

The previous prime is 78831679. The next prime is 78831721. The reversal of 78831691 is 19613887.

It is a weak prime.

It is an emirp because it is prime and its reverse (19613887) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78831691 - 2⁵ = 78831659 is a prime.

It is not a weakly prime, because it can be changed into another prime (78831671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39415845 + 39415846.

It is an arithmetic number, because the mean of its divisors is an integer number (39415846).

Almost surely, 2^78831691 is an apocalyptic number.

78831691 is a deficient number, since it is larger than the sum of its proper divisors (1).

78831691 is an equidigital number, since it uses as much as digits as its factorization.

78831691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 43.

The square root of 78831691 is about 8878.7212480176. The cubic root of 78831691 is about 428.7791057655.

The spelling of 78831691 in words is "seventy-eight million, eight hundred thirty-one thousand, six hundred ninety-one".