198978979 has 4 divisors (see below), whose sum is σ = 199087200. Its totient is φ = 198870760.

The previous prime is 198978973. The next prime is 198979009. The reversal of 198978979 is 979879891.

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

It is a cyclic number.

It is not a de Polignac number, because 198978979 - 2⁷ = 198978851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (198978973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51304 + ... + 55045.

It is an arithmetic number, because the mean of its divisors is an integer number (49771800).

Almost surely, 2^198978979 is an apocalyptic number.

198978979 is a deficient number, since it is larger than the sum of its proper divisors (108221).

198978979 is a wasteful number, since it uses less digits than its factorization.

198978979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108220.

The product of its digits is 20575296, while the sum is 67.

The square root of 198978979 is about 14105.9908903983. The cubic root of 198978979 is about 583.8066881841.

The spelling of 198978979 in words is "one hundred ninety-eight million, nine hundred seventy-eight thousand, nine hundred seventy-nine".