243891 has 10 divisors (see below), whose sum is σ = 364452. Its totient is φ = 162540.

The previous prime is 243889. The next prime is 243911. The reversal of 243891 is 198342.

243891 is nontrivially palindromic in base 16.

It is not a de Polignac number, because 243891 - 2¹ = 243889 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (243851) 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 9 ways as a sum of consecutive naturals, for example, 1425 + ... + 1586.

2²⁴³⁸⁹¹ is an apocalyptic number.

243891 is a deficient number, since it is larger than the sum of its proper divisors (120561).

243891 is an equidigital number, since it uses as much as digits as its factorization.

243891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3023 (or 3014 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 243891 is about 493.8532170595. The cubic root of 243891 is about 62.4786914026.

The spelling of 243891 in words is "two hundred forty-three thousand, eight hundred ninety-one".