231221320 has 128 divisors (see below), whose sum is σ = 591338880. Its totient is φ = 81312000.

The previous prime is 231221299. The next prime is 231221381. The reversal of 231221320 is 23122132.

It is a junction number, because it is equal to n+sod(n) for n = 231221294 and 231221303.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2289270 + ... + 2289370.

It is an arithmetic number, because the mean of its divisors is an integer number (4619835).

Almost surely, 2^231221320 is an apocalyptic number.

231221320 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 231221320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (295669440).

231221320 is an abundant number, since it is smaller than the sum of its proper divisors (360117560).

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

231221320 is a wasteful number, since it uses less digits than its factorization.

231221320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188 (or 162 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 231221320 is about 15205.9633039147. The cubic root of 231221320 is about 613.7751372020.

Adding to 231221320 its reverse (23122132), we get a palindrome (254343452).

It can be divided in two parts, 23122 and 1320, that added together give a palindrome (24442).

The spelling of 231221320 in words is "two hundred thirty-one million, two hundred twenty-one thousand, three hundred twenty".