78785191889 has 2 divisors, whose sum is σ = 78785191890. Its totient is φ = 78785191888.

The previous prime is 78785191871. The next prime is 78785191973. The reversal of 78785191889 is 98819158787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57129126289 + 21656065600 = 239017^2 + 147160^2 .

It is a cyclic number.

It is not a de Polignac number, because 78785191889 - 2⁸ = 78785191633 is a prime.

It is not a weakly prime, because it can be changed into another prime (78785191789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39392595944 + 39392595945.

It is an arithmetic number, because the mean of its divisors is an integer number (39392595945).

Almost surely, 2^78785191889 is an apocalyptic number.

It is an amenable number.

78785191889 is a deficient number, since it is larger than the sum of its proper divisors (1).

78785191889 is an equidigital number, since it uses as much as digits as its factorization.

78785191889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81285120, while the sum is 71.

The spelling of 78785191889 in words is "seventy-eight billion, seven hundred eighty-five million, one hundred ninety-one thousand, eight hundred eighty-nine".