1998778894 has 24 divisors (see below), whose sum is σ = 3490739280. Its totient is φ = 855864576.

The previous prime is 1998778879. The next prime is 1998778897. The reversal of 1998778894 is 4988778991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998778897) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 110887 + ... + 127645.

It is an arithmetic number, because the mean of its divisors is an integer number (145447470).

Almost surely, 2^1998778894 is an apocalyptic number.

1998778894 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

1998778894 is a deficient number, since it is larger than the sum of its proper divisors (1491960386).

1998778894 is a wasteful number, since it uses less digits than its factorization.

1998778894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17992 (or 17985 counting only the distinct ones).

The product of its digits is 73156608, while the sum is 70.

The square root of 1998778894 is about 44707.7050853653. The cubic root of 1998778894 is about 1259.6645814997.

The spelling of 1998778894 in words is "one billion, nine hundred ninety-eight million, seven hundred seventy-eight thousand, eight hundred ninety-four".