21131232320 has 112 divisors (see below), whose sum is σ = 55824120000. Its totient is φ = 7553771520.

The previous prime is 21131232293. The next prime is 21131232329. The reversal of 21131232320 is 2323213112.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21131232292 and 21131232301.

It is not an unprimeable number, because it can be changed into a prime (21131232329) 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, 156806 + ... + 258554.

Almost surely, 2^21131232320 is an apocalyptic number.

21131232320 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 21131232320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27912060000).

21131232320 is an abundant number, since it is smaller than the sum of its proper divisors (34692887680).

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

21131232320 is a wasteful number, since it uses less digits than its factorization.

21131232320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101836 (or 101826 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21131232320 its reverse (2323213112), we get a palindrome (23454445432).

The spelling of 21131232320 in words is "twenty-one billion, one hundred thirty-one million, two hundred thirty-two thousand, three hundred twenty".