231121440 has 144 divisors (see below), whose sum is σ = 860461056. Its totient is φ = 56025600.

The previous prime is 231121417. The next prime is 231121447. The reversal of 231121440 is 44121132.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (231121447) 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 23 ways as a sum of consecutive naturals, for example, 8545 + ... + 23135.

It is an arithmetic number, because the mean of its divisors is an integer number (5975424).

Almost surely, 2^231121440 is an apocalyptic number.

231121440 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 231121440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (430230528).

231121440 is an abundant number, since it is smaller than the sum of its proper divisors (629339616).

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

231121440 is a wasteful number, since it uses less digits than its factorization.

231121440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14623 (or 14612 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 231121440 is about 15202.6787113324. The cubic root of 231121440 is about 613.6867475877.

Adding to 231121440 its reverse (44121132), we get a palindrome (275242572).

The spelling of 231121440 in words is "two hundred thirty-one million, one hundred twenty-one thousand, four hundred forty".