191997 has 16 divisors (see below), whose sum is σ = 306880. Its totient is φ = 117936.

The previous prime is 191977. The next prime is 191999. The reversal of 191997 is 799191.

191997 is nontrivially palindromic in base 12.

It is not a de Polignac number, because 191997 - 2¹¹ = 189949 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78 + ... + 624.

It is an arithmetic number, because the mean of its divisors is an integer number (19180).

2¹⁹¹⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

191997 is a deficient number, since it is larger than the sum of its proper divisors (114883).

191997 is a wasteful number, since it uses less digits than its factorization.

191997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 569 (or 563 counting only the distinct ones).

The product of its digits is 5103, while the sum is 36.

The square root of 191997 is about 438.1746227248. The cubic root of 191997 is about 57.6896823421.

It can be divided in two parts, 1919 and 97, that added together give a triangular number (2016 = T₆₃).

The spelling of 191997 in words is "one hundred ninety-one thousand, nine hundred ninety-seven".