249991 has 8 divisors (see below), whose sum is σ = 290304. Its totient is φ = 210840.

The previous prime is 249989. The next prime is 250007. The reversal of 249991 is 199942.

249991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 249991 - 2¹ = 249989 is a prime.

249991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (249911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 246 + ... + 748.

It is an arithmetic number, because the mean of its divisors is an integer number (36288).

249991 is a Friedman number, since it can be written as (491+9)^2-9, using all its digits and the basic arithmetic operations.

2²⁴⁹⁹⁹¹ is an apocalyptic number.

249991 is a deficient number, since it is larger than the sum of its proper divisors (40313).

249991 is an equidigital number, since it uses as much as digits as its factorization.

249991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581.

The product of its digits is 5832, while the sum is 34.

The square root of 249991 is about 499.9909999190. The cubic root of 249991 is about 62.9952965330.

The spelling of 249991 in words is "two hundred forty-nine thousand, nine hundred ninety-one".