19910454779 has 2 divisors, whose sum is σ = 19910454780. Its totient is φ = 19910454778.

The previous prime is 19910454743. The next prime is 19910454797. The reversal of 19910454779 is 97745401991.

Together with next prime (19910454797) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19910454779 - 2⁸ = 19910454523 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (19910454709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9955227389 + 9955227390.

It is an arithmetic number, because the mean of its divisors is an integer number (9955227390).

Almost surely, 2^19910454779 is an apocalyptic number.

19910454779 is a deficient number, since it is larger than the sum of its proper divisors (1).

19910454779 is an equidigital number, since it uses as much as digits as its factorization.

19910454779 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2857680, while the sum is 56.

The spelling of 19910454779 in words is "nineteen billion, nine hundred ten million, four hundred fifty-four thousand, seven hundred seventy-nine".