21232031220 has 144 divisors (see below), whose sum is σ = 66178174608. Its totient is φ = 5506744320.

The previous prime is 21232031167. The next prime is 21232031269. The reversal of 21232031220 is 2213023212.

21232031220 is a `hidden beast` number, since 2 + 12 + 320 + 312 + 20 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 1340877924 + 19891153296 = 36618^2 + 141036^2 .

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 = 21232031193 and 21232031202.

It is a congruent number.

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, 2482792 + ... + 2491328.

It is an arithmetic number, because the mean of its divisors is an integer number (459570657).

Almost surely, 2^21232031220 is an apocalyptic number.

21232031220 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 21232031220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33089087304).

21232031220 is an abundant number, since it is smaller than the sum of its proper divisors (44946143388).

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

21232031220 is a wasteful number, since it uses less digits than its factorization.

21232031220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8930 (or 8925 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

Adding to 21232031220 its reverse (2213023212), we get a palindrome (23445054432).

The spelling of 21232031220 in words is "twenty-one billion, two hundred thirty-two million, thirty-one thousand, two hundred twenty".