199665 has 40 divisors (see below), whose sum is σ = 392040. Its totient is φ = 96768.

The previous prime is 199657. The next prime is 199669. The reversal of 199665 is 566991.

It can be written as a sum of positive squares in 4 ways, for example, as 42849 + 156816 = 207^2 + 396^2 .

It is not a de Polignac number, because 199665 - 2³ = 199657 is a prime.

It is a super-2 number, since 2×199665² = 79732224450, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

Its product of digits (14580) is a multiple of the sum of its prime divisors (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199669) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 6871 + ... + 6899.

It is an arithmetic number, because the mean of its divisors is an integer number (9801).

2¹⁹⁹⁶⁶⁵ is an apocalyptic number.

199665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

199665 is a deficient number, since it is larger than the sum of its proper divisors (192375).

199665 is a wasteful number, since it uses less digits than its factorization.

199665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 54 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 199665 is about 446.8388971430. The cubic root of 199665 is about 58.4476849854.

The spelling of 199665 in words is "one hundred ninety-nine thousand, six hundred sixty-five".