198993978 has 24 divisors (see below), whose sum is σ = 434450016. Its totient is φ = 65824200.

The previous prime is 198993967. The next prime is 198994009. The reversal of 198993978 is 879399891.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39838 + ... + 44553.

It is an arithmetic number, because the mean of its divisors is an integer number (18102084).

Almost surely, 2^198993978 is an apocalyptic number.

198993978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

198993978 is an abundant number, since it is smaller than the sum of its proper divisors (235456038).

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

198993978 is a wasteful number, since it uses less digits than its factorization.

198993978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84530 (or 84527 counting only the distinct ones).

The product of its digits is 8817984, while the sum is 63.

The square root of 198993978 is about 14106.5225339203. The cubic root of 198993978 is about 583.8213568969.

The spelling of 198993978 in words is "one hundred ninety-eight million, nine hundred ninety-three thousand, nine hundred seventy-eight".