199581978 has 16 divisors (see below), whose sum is σ = 399409920. Its totient is φ = 66486336.

The previous prime is 199581961. The next prime is 199581979. The reversal of 199581978 is 879185991.

199581978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (199581979) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1303 + ... + 20021.

It is an arithmetic number, because the mean of its divisors is an integer number (24963120).

Almost surely, 2^199581978 is an apocalyptic number.

199581978 is an abundant number, since it is smaller than the sum of its proper divisors (199827942).

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

199581978 is a wasteful number, since it uses less digits than its factorization.

199581978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20501.

The product of its digits is 1632960, while the sum is 57.

The square root of 199581978 is about 14127.3485835099. The cubic root of 199581978 is about 584.3958288705.

The spelling of 199581978 in words is "one hundred ninety-nine million, five hundred eighty-one thousand, nine hundred seventy-eight".