198991178 has 4 divisors (see below), whose sum is σ = 298486770. Its totient is φ = 99495588.

The previous prime is 198991157. The next prime is 198991183. The reversal of 198991178 is 871199891.

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., 193293409 + 5697769 = 13903^2 + 2387^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49747793 + ... + 49747796.

Almost surely, 2^198991178 is an apocalyptic number.

198991178 is a deficient number, since it is larger than the sum of its proper divisors (99495592).

198991178 is an equidigital number, since it uses as much as digits as its factorization.

198991178 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99495591.

The product of its digits is 326592, while the sum is 53.

The square root of 198991178 is about 14106.4232887008. The cubic root of 198991178 is about 583.8186186106.

The spelling of 198991178 in words is "one hundred ninety-eight million, nine hundred ninety-one thousand, one hundred seventy-eight".