199857978 has 24 divisors (see below), whose sum is σ = 433375488. Its totient is φ = 66565512.

The previous prime is 199857949. The next prime is 199857989. The reversal of 199857978 is 879758991.

It is a super-2 number, since 2×199857978² = 79886422740496968, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22951 + ... + 30437.

It is an arithmetic number, because the mean of its divisors is an integer number (18057312).

Almost surely, 2^199857978 is an apocalyptic number.

199857978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

199857978 is an abundant number, since it is smaller than the sum of its proper divisors (233517510).

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

199857978 is a wasteful number, since it uses less digits than its factorization.

199857978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8978 (or 8975 counting only the distinct ones).

The product of its digits is 11430720, while the sum is 63.

The square root of 199857978 is about 14137.1134960430. The cubic root of 199857978 is about 584.6650899149.

The spelling of 199857978 in words is "one hundred ninety-nine million, eight hundred fifty-seven thousand, nine hundred seventy-eight".