1219391778 has 24 divisors (see below), whose sum is σ = 2680647984. Its totient is φ = 369512440.

The previous prime is 1219391743. The next prime is 1219391779. The reversal of 1219391778 is 8771939121.

It is not an unprimeable number, because it can be changed into a prime (1219391779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 839076 + ... + 840527.

It is an arithmetic number, because the mean of its divisors is an integer number (111693666).

Almost surely, 2^1219391778 is an apocalyptic number.

1219391778 is an abundant number, since it is smaller than the sum of its proper divisors (1461256206).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1219391778 is a wasteful number, since it uses less digits than its factorization.

1219391778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1679630 (or 1679619 counting only the distinct ones).

The product of its digits is 190512, while the sum is 48.

The square root of 1219391778 is about 34919.7906351112. The cubic root of 1219391778 is about 1068.3521314273.

The spelling of 1219391778 in words is "one billion, two hundred nineteen million, three hundred ninety-one thousand, seven hundred seventy-eight".