231440 has 40 divisors (see below), whose sum is σ = 589248. Its totient is φ = 83840.

The previous prime is 231433. The next prime is 231443. The reversal of 231440 is 44132.

It is a tau number, because it is divible by the number of its divisors (40).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 231440.

It is not an unprimeable number, because it can be changed into a prime (231443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 749 + ... + 1011.

2²³¹⁴⁴⁰ is an apocalyptic number.

231440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 231440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (294624).

231440 is an abundant number, since it is smaller than the sum of its proper divisors (357808).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

231440 is a wasteful number, since it uses less digits than its factorization.

231440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 231440 is about 481.0821135731. The cubic root of 231440 is about 61.3968571002.

Adding to 231440 its reverse (44132), we get a palindrome (275572).

The spelling of 231440 in words is "two hundred thirty-one thousand, four hundred forty".