231721320 has 128 divisors (see below), whose sum is σ = 738201600. Its totient is φ = 58063104.

The previous prime is 231721291. The next prime is 231721331. The reversal of 231721320 is 23127132.

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, 162129 + ... + 163551.

It is an arithmetic number, because the mean of its divisors is an integer number (5767200).

Almost surely, 2^231721320 is an apocalyptic number.

231721320 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 231721320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (369100800).

231721320 is an abundant number, since it is smaller than the sum of its proper divisors (506480280).

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

231721320 is a wasteful number, since it uses less digits than its factorization.

231721320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1519 (or 1515 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 231721320 is about 15222.3953437033. The cubic root of 231721320 is about 614.2172340154.

Adding to 231721320 its reverse (23127132), we get a palindrome (254848452).

The spelling of 231721320 in words is "two hundred thirty-one million, seven hundred twenty-one thousand, three hundred twenty".