231521020 has 48 divisors (see below), whose sum is σ = 504177408. Its totient is φ = 89210880.

The previous prime is 231521009. The next prime is 231521021. The reversal of 231521020 is 20125132.

It is a junction number, because it is equal to n+sod(n) for n = 231520985 and 231521003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231521021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 158614 + ... + 160066.

It is an arithmetic number, because the mean of its divisors is an integer number (10503696).

Almost surely, 2^231521020 is an apocalyptic number.

231521020 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 231521020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (252088704).

231521020 is an abundant number, since it is smaller than the sum of its proper divisors (272656388).

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

231521020 is a wasteful number, since it uses less digits than its factorization.

231521020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1750 (or 1748 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 231521020 is about 15215.8147990832. The cubic root of 231521020 is about 614.0402064586.

Adding to 231521020 its reverse (20125132), we get a palindrome (251646152).

The spelling of 231521020 in words is "two hundred thirty-one million, five hundred twenty-one thousand, twenty".