778109491 has 2 divisors, whose sum is σ = 778109492. Its totient is φ = 778109490.

The previous prime is 778109441. The next prime is 778109509. The reversal of 778109491 is 194901877.

It is a strong prime.

It is an emirp because it is prime and its reverse (194901877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 778109491 - 2²⁹ = 241238579 is a prime.

It is not a weakly prime, because it can be changed into another prime (778109441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389054745 + 389054746.

It is an arithmetic number, because the mean of its divisors is an integer number (389054746).

Almost surely, 2^778109491 is an apocalyptic number.

778109491 is a deficient number, since it is larger than the sum of its proper divisors (1).

778109491 is an equidigital number, since it uses as much as digits as its factorization.

778109491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 127008, while the sum is 46.

The square root of 778109491 is about 27894.6140141784. The cubic root of 778109491 is about 919.7721123493.

The spelling of 778109491 in words is "seven hundred seventy-eight million, one hundred nine thousand, four hundred ninety-one".