199639 has 4 divisors (see below), whose sum is σ = 217800. Its totient is φ = 181480.

The previous prime is 199637. The next prime is 199657. The reversal of 199639 is 936991.

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 199639 - 2¹ = 199637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 199598 and 199607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9064 + ... + 9085.

It is an arithmetic number, because the mean of its divisors is an integer number (54450).

2¹⁹⁹⁶³⁹ is an apocalyptic number.

199639 is a deficient number, since it is larger than the sum of its proper divisors (18161).

199639 is a wasteful number, since it uses less digits than its factorization.

199639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18160.

The product of its digits is 13122, while the sum is 37.

The square root of 199639 is about 446.8098029363. The cubic root of 199639 is about 58.4451478928.

It can be divided in two parts, 199 and 639, that added together give a palindrome (838).

The spelling of 199639 in words is "one hundred ninety-nine thousand, six hundred thirty-nine".