191990 has 16 divisors (see below), whose sum is σ = 351648. Its totient is φ = 75456.

The previous prime is 191977. The next prime is 191999. The reversal of 191990 is 99191.

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

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 599 + ... + 861.

It is an arithmetic number, because the mean of its divisors is an integer number (21978).

2¹⁹¹⁹⁹⁰ is an apocalyptic number.

191990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

191990 is a deficient number, since it is larger than the sum of its proper divisors (159658).

191990 is a wasteful number, since it uses less digits than its factorization.

191990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

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

The square root of 191990 is about 438.1666349689. The cubic root of 191990 is about 57.6889812327.

The spelling of 191990 in words is "one hundred ninety-one thousand, nine hundred ninety".