190991 has 8 divisors (see below), whose sum is σ = 202368. Its totient is φ = 180000.

The previous prime is 190979. The next prime is 190997. The reversal of 190991 is 199091.

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 190991 - 2¹⁰ = 189967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (190997) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1841 + ... + 1941.

It is an arithmetic number, because the mean of its divisors is an integer number (25296).

2¹⁹⁰⁹⁹¹ is an apocalyptic number.

190991 is a deficient number, since it is larger than the sum of its proper divisors (11377).

190991 is a wasteful number, since it uses less digits than its factorization.

190991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 193.

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 190991 is about 437.0251708998. The cubic root of 190991 is about 57.5887476412.

Subtracting 190991 from its reverse (199091), we obtain a square (8100 = 90²).

The spelling of 190991 in words is "one hundred ninety thousand, nine hundred ninety-one".