199661 has 8 divisors (see below), whose sum is σ = 249024. Its totient is φ = 155520.

The previous prime is 199657. The next prime is 199669. The reversal of 199661 is 166991.

199661 = T₃₀ + T₃₁ + ... + T₁₀₆.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 199661 - 2² = 199657 is a prime.

199661 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

It is a nialpdrome in base 12.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1220 + ... + 1373.

It is an arithmetic number, because the mean of its divisors is an integer number (31128).

2¹⁹⁹⁶⁶¹ is an apocalyptic number.

199661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

199661 is a deficient number, since it is larger than the sum of its proper divisors (49363).

199661 is a wasteful number, since it uses less digits than its factorization.

199661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2611.

The product of its digits is 2916, while the sum is 32.

The square root of 199661 is about 446.8344212345. The cubic root of 199661 is about 58.4472946778.

The spelling of 199661 in words is "one hundred ninety-nine thousand, six hundred sixty-one".