199840 has 24 divisors (see below), whose sum is σ = 472500. Its totient is φ = 79872.

The previous prime is 199831. The next prime is 199853. The reversal of 199840 is 48991.

It can be written as a sum of positive squares in 2 ways, for example, as 197136 + 2704 = 444^2 + 52^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

199840 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 465 + ... + 784.

2¹⁹⁹⁸⁴⁰ is an apocalyptic number.

199840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

199840 is an abundant number, since it is smaller than the sum of its proper divisors (272660).

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

199840 is a wasteful number, since it uses less digits than its factorization.

199840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1264 (or 1256 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 199840 is about 447.0346742704. The cubic root of 199840 is about 58.4647558425.

Subtracting from 199840 its sum of digits (31), we obtain a square (199809 = 447²).

The spelling of 199840 in words is "one hundred ninety-nine thousand, eight hundred forty".