240991 has 4 divisors (see below), whose sum is σ = 245592. Its totient is φ = 236392.

The previous prime is 240967. The next prime is 240997. The reversal of 240991 is 199042.

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

It is a cyclic number.

It is not a de Polignac number, because 240991 - 2⁵ = 240959 is a prime.

It is an Ulam number.

It is a Duffinian number.

240991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (240997) 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, 2221 + ... + 2326.

It is an arithmetic number, because the mean of its divisors is an integer number (61398).

240991 is a Friedman number, since it can be written as 491^2-90, using all its digits and the basic arithmetic operations.

2²⁴⁰⁹⁹¹ is an apocalyptic number.

240991 is a deficient number, since it is larger than the sum of its proper divisors (4601).

240991 is an equidigital number, since it uses as much as digits as its factorization.

240991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4600.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 240991 is about 490.9083417503. The cubic root of 240991 is about 62.2300678646.

It can be divided in two parts, 2409 and 91, that added together give a square (2500 = 50²).

The spelling of 240991 in words is "two hundred forty thousand, nine hundred ninety-one".