21231121320 has 192 divisors, whose sum is σ = 69759144000. Its totient is φ = 5599770624.

The previous prime is 21231121259. The next prime is 21231121333. The reversal of 21231121320 is 2312113212.

21231121320 is a `hidden beast` number, since 2 + 12 + 311 + 21 + 320 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 21231121293 and 21231121302.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 16862851 + ... + 16864109.

It is an arithmetic number, because the mean of its divisors is an integer number (363328875).

Almost surely, 2^21231121320 is an apocalyptic number.

21231121320 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 21231121320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34879572000).

21231121320 is an abundant number, since it is smaller than the sum of its proper divisors (48528022680).

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

21231121320 is a wasteful number, since it uses less digits than its factorization.

21231121320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1752 (or 1745 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21231121320 its reverse (2312113212), we get a palindrome (23543234532).

The spelling of 21231121320 in words is "twenty-one billion, two hundred thirty-one million, one hundred twenty-one thousand, three hundred twenty".