231221329920 has 1280 divisors, whose sum is σ = 1004856019200. Its totient is φ = 49686773760.

The previous prime is 231221329907. The next prime is 231221329979. The reversal of 231221329920 is 29923122132.

231221329920 is a `hidden beast` number, since 23 + 1 + 221 + 329 + 92 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1280).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1765048255 + ... + 1765048385.

It is an arithmetic number, because the mean of its divisors is an integer number (785043765).

Almost surely, 2^231221329920 is an apocalyptic number.

231221329920 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 231221329920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (502428009600).

231221329920 is an abundant number, since it is smaller than the sum of its proper divisors (773634689280).

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

231221329920 is an equidigital number, since it uses as much as digits as its factorization.

231221329920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The spelling of 231221329920 in words is "two hundred thirty-one billion, two hundred twenty-one million, three hundred twenty-nine thousand, nine hundred twenty".