1999378786 has 4 divisors (see below), whose sum is σ = 2999068182. Its totient is φ = 999689392.

The previous prime is 1999378751. The next prime is 1999378831. The reversal of 1999378786 is 6878739991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1885209561 + 114169225 = 43419^2 + 10685^2 .

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499844695 + ... + 499844698.

Almost surely, 2^1999378786 is an apocalyptic number.

1999378786 is a deficient number, since it is larger than the sum of its proper divisors (999689396).

1999378786 is an equidigital number, since it uses as much as digits as its factorization.

1999378786 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999689395.

The product of its digits is 41150592, while the sum is 67.

The square root of 1999378786 is about 44714.4136269280. The cubic root of 1999378786 is about 1259.7905896208.

The spelling of 1999378786 in words is "one billion, nine hundred ninety-nine million, three hundred seventy-eight thousand, seven hundred eighty-six".