191989 has 4 divisors (see below), whose sum is σ = 219424. Its totient is φ = 164556.

The previous prime is 191977. The next prime is 191999. The reversal of 191989 is 989191.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 191989 - 2⁷ = 191861 is a prime.

It is a super-2 number, since 2×191989² = 73719552242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13707 + ... + 13720.

It is an arithmetic number, because the mean of its divisors is an integer number (54856).

2¹⁹¹⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

191989 is a deficient number, since it is larger than the sum of its proper divisors (27435).

191989 is an equidigital number, since it uses as much as digits as its factorization.

191989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27434.

The product of its digits is 5832, while the sum is 37.

The square root of 191989 is about 438.1654938491. The cubic root of 191989 is about 57.6888810728.

The spelling of 191989 in words is "one hundred ninety-one thousand, nine hundred eighty-nine".