78771691 has 2 divisors, whose sum is σ = 78771692. Its totient is φ = 78771690.

The previous prime is 78771677. The next prime is 78771697. The reversal of 78771691 is 19617787.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78771691 - 2¹¹ = 78769643 is a prime.

It is not a weakly prime, because it can be changed into another prime (78771697) 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, 39385845 + 39385846.

It is an arithmetic number, because the mean of its divisors is an integer number (39385846).

Almost surely, 2^78771691 is an apocalyptic number.

78771691 is a deficient number, since it is larger than the sum of its proper divisors (1).

78771691 is an equidigital number, since it uses as much as digits as its factorization.

78771691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 148176, while the sum is 46.

The square root of 78771691 is about 8875.3417398994. The cubic root of 78771691 is about 428.6702947201.

The spelling of 78771691 in words is "seventy-eight million, seven hundred seventy-one thousand, six hundred ninety-one".