21212232320 has 256 divisors, whose sum is σ = 55232755200. Its totient is φ = 7763558400.

The previous prime is 21212232317. The next prime is 21212232343. The reversal of 21212232320 is 2323221212.

It is a happy number.

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 = 21212232292 and 21212232301.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 78273785 + ... + 78274055.

It is an arithmetic number, because the mean of its divisors is an integer number (215752950).

Almost surely, 2^21212232320 is an apocalyptic number.

21212232320 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 21212232320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27616377600).

21212232320 is an abundant number, since it is smaller than the sum of its proper divisors (34020522880).

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

21212232320 is a wasteful number, since it uses less digits than its factorization.

21212232320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507 (or 495 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21212232320 its reverse (2323221212), we get a palindrome (23535453532).

It can be divided in two parts, 212122 and 32320, that added together give a palindrome (244442).

The spelling of 21212232320 in words is "twenty-one billion, two hundred twelve million, two hundred thirty-two thousand, three hundred twenty".