191381 has 4 divisors (see below), whose sum is σ = 193452. Its totient is φ = 189312.

The previous prime is 191353. The next prime is 191413. The reversal of 191381 is 183191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 62500 + 128881 = 250^2 + 359^2 .

It is a cyclic number.

It is not a de Polignac number, because 191381 - 2¹⁰ = 190357 is a prime.

It is a super-2 number, since 2×191381² = 73253374322, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 191381.

It is not an unprimeable number, because it can be changed into a prime (191341) 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 3 ways as a sum of consecutive naturals, for example, 890 + ... + 1083.

It is an arithmetic number, because the mean of its divisors is an integer number (48363).

2¹⁹¹³⁸¹ is an apocalyptic number.

It is an amenable number.

191381 is a deficient number, since it is larger than the sum of its proper divisors (2071).

191381 is an equidigital number, since it uses as much as digits as its factorization.

191381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2070.

The product of its digits is 216, while the sum is 23.

The square root of 191381 is about 437.4711419054. The cubic root of 191381 is about 57.6279193675.

It can be divided in two parts, 191 and 381, that multiplied together give a triangular number (72771 = T₃₈₁).

The spelling of 191381 in words is "one hundred ninety-one thousand, three hundred eighty-one".