198566904978 has 64 divisors (see below), whose sum is σ = 475571416320. Its totient is φ = 61050122496.

The previous prime is 198566904947. The next prime is 198566904989. The reversal of 198566904978 is 879409665891.

198566904978 is a `hidden beast` number, since 19 + 8 + 566 + 9 + 0 + 49 + 7 + 8 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 801451 + ... + 1019537.

It is an arithmetic number, because the mean of its divisors is an integer number (7430803380).

Almost surely, 2^198566904978 is an apocalyptic number.

198566904978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 198566904978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (237785708160).

198566904978 is an abundant number, since it is smaller than the sum of its proper divisors (277004511342).

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

198566904978 is a wasteful number, since it uses less digits than its factorization.

198566904978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219408 (or 219402 counting only the distinct ones).

The product of its (nonzero) digits is 235146240, while the sum is 72.

The spelling of 198566904978 in words is "one hundred ninety-eight billion, five hundred sixty-six million, nine hundred four thousand, nine hundred seventy-eight".